The Employer comes late, the manager ...... him. (complete) with the right decision

subjective question but very good one.
managers are tasked and not 9-6 individuals.
many work from home or out of working hrs and get existed as result to over commitment to their job.
think again before judging them based on what you see.
get closer look into what they have been doing that resulted in that delay and set them up right as they have to lead by example.

The question is what will I do as a manager if my employer comes late? I will say good morning to her/him.

for me...
always asking about the reason and how can i help him...
and it depend on the situation, in normal case verbal warning is enough...
and if he used to come late we will set together and decide what kind of punishment we will take...
i am manager but in the same time we are a team.

If boss have nice heart.then employee always got relaxation to make sad face in front of him.

Thanks for all whom answered my Q but PLZ note that I'm talking about a problem happens every day in every firm ...
and all i ask is your opinion WHAT WILL YOU DO IF YOU ARE A MANAGER

It depends on the culture of the organization and what role the person plays.
In today's world flexibility is allowed, if some body comes late he will go late and make up his missing time within that week.
Every employee is assigned to a certain work and has a deadlines to complete.
Management ensures whether flexibility should be allowed or may cause counter productive.
If some body is in public service such as (Hospital, Bank, Bill payment center etc) j where a regular timely attendance is required, in such a case flexibility does not permit but if some one is working as a developer/coder/sales person, he does not need to maintain his office time ie.9-5 and could be allowed flexible hours including remotely working from home on certain days in a week.
You need to keep your business running at the same time keep your people motivated for better and continuous business growth and success.

Although I hate bossism but my friend Mr.
Chang always say that there are two golden rules in the world.
Rule No.1 : Boss is Always right.
Rule No.2 : If he is wrong, again see rule No.1 But from my point of view, and being positive,actually Employer took care of lot of assignments, so he may be busy in somewhere, for which we do not have information.
Secondly with little bit reservation, he is independent in his behavior as business belongs to him not us.

the manager should LEAD BY EXAMPLE and always have an open door policy.
It is the mangers job to lay out the rules before the employee is hired.
What i would do is the first time is a warning second time just go home third time he will be replaced as soon as you find someone to replace him.
you don't want to fire an employee without having a replacement already lined up

fristly must be write that he come late in your agenda time-date and if frist time worrning him if this is habite must be punched by salary detection

if he used to come late he will warm him if he come late just one time he will ask him, what is the reason of coming late this time