In today's world a company's value is dependent on the value of its own shares in stock market. Do you agree?

Market value is also commonly used to refer to the market capitalization of a publicly-traded company, and is obtained by multiplying the number of its outstanding shares by the current share price. Market value is easiest to determine for exchange-traded instruments such as stocks and futures, since their market prices are widely disseminated and easily available, but is a little more challenging to ascertain for over-the-counter instruments like fixed income securities. However, the greatest difficulty in determining market value lies in estimating the value of illiquid assets like real estate and businesses, which may necessitate the use of real estate appraisers and business valuation experts respectively.

In normal circumstances stock market valuation IS the value of the company. A thing is only worth as much a somebody is willing to pay for it.

Unfortunately yes but mostly it does not reflect the true values as it has large scope for manipulation.

I don't. The stock market is changeable and is ruled by alot of factors and the political conditions. So the company may come up or collapse according to the mood of the stock market.