Do you think that Project Manager should have Technical expertise?

Not necessary to be an expert. If the Project Manager has a sufficient level of technical and domain expertise, it is sufficient to succeed in his/her role.

I think that a Project Manager should have a Technical skills, this will help him to understand the mecanic of the project and help project team to face issues.

With no technical skills (domain of project/ competencies) the Project Manager may loose leadership.

I think Project Manager with technical knowledge will be better. But if project manger had team of technical knowledge who they have good experience more than him in that section .he must  balance their decisions with him and usually the two decisions will be near of each other.

As well as if he haven't any technical knowledge he will follow the technical knowledge team and they will carry the full responsibly of their decisions. 

Although its not essential to have technical knowledge when managing a project it is highly advantageous in certain circumstances. When an organisation has limited resource and is not able to commit all the resources and people required to deliver the project having technical awareness of what is being delivered as well as the workings of the organisation will help the project to succeed. Caution needs to be applied however to ensure that as a project manager you maintain impartiality to the direction the project takes maintaining a clear focus on the products and deliverable's you will ultimately be measured against. 

Good question, well I would say there are two kinds of project managers if we look at it broadly:

Technical Project Manager:

In most of the cases has worked his way from a technical background to a technical team lead and finally taken an entry into the project managers office as a project manager. 

Positives: 

1. Respected by the team due to hands of knowledge of the technical issue.

2. A comfortable point of contact for the technical team to sort out technical glitches during the project.

Drawbacks:

1. Knowledge and inclination towards technical aspects of the projects leads to manager micro managing the technicalities of the project and eventually losing focus on the managerial aspects.

2. In some cases lacks the business perspective or domain knowledge and is over depended on the business analyst for end user requirements process.

3. In some cases finds it difficult to accept the management perspective and sours relations with the management which in turn leads to a high pressure work environment for the technical team.

Non Technical Project Manager: These guys tend to good at the domain side of the project. Example lets say an organisation caters its technical expertise to the aviation industry. These guys have a good knowledge about the aviation business process. They come from varied backgrounds like BPR BPM etc.

Positives:

1. Finds it comfortable to interact with the end user and attains a birds eye view of the business requirements.

2. Sharing a good rapport and trust with the end user attimes makes him also partly a guy bringing in new project from the client.

3. As above ability to get new projects means an increase in the company revenue stream and thus also shares a good rapport with the management.

4. Good rapport with the management ensures a good percentage of company budget allocated to him and in turn a good salary appraisal for his technical team.

Drawbacks:

1. The technical team lead is under sever stress since in this case he is the final point of contact for technical issues.

2. The team environment tends to lean towards who is the managers best man rather that the actual work done.

3. PMO tends to stay detached from the technical team and focuses only on technical deliveries rather than nurturing the team.

So I would have to say a bit of both technical and business skills are essential but again no body is a perfect project manager when we come to think of it :-)

It depends on the project type anyway.

But if I was to hire a PM with technical experts or without, sure I will prefer the that has technical experts over the one without.

Sure! A project Manager have technical experties.

It is highly recommended for the project manager to have technical expertise

I think it should be an advantage because he could look twice the project with his own point of view and get the advice of his technical experts. It leads to a better checking of the technical choices.

Nevertheless, the fact is if the project manager don't even take care of the advice of the technical experts, it could have bad consequences as loss of respect or teamspirit beetween members. The technical experts can feel useless at the end and be disturbed on its role in the team.

In my mind, i see that the lack of technical skill can be very harmful for the leader position. If the technical choices are bad, you have to justify the mistakes to your boss and not being able to understand them won't be very appreciated...

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I think and this my private opinion He/She must strictly has enough technical information  

Not necessarily. Technical expertise can definitely help a project manager understand the technical aspects of the project in many ways. 

But i have seen amazing managers without the technical expertise of their projects. In-fact a good project manager should work in multiple domains to gain experience.