If I get a permanent residency status through Quebeck provincial nominee program will it be must for me to stay in Quebec even when I will not be able to get a job (as it happens with the most new immigrants in this country).
Can I look for a job and move to another province (when I find a job in another province in Canada), or I still must stay in Quebeck - if yes, for how long?
Yes, but the OP should read the agreement that s/he signed with the province. They do have the right to lift the PNP certificate if the applicant doesn't attempt to settle in the province that nominated.
Make good on the agreement you signed and start out in the province that nominated you. Try to find a job there. If you are unable to find a job there but find a job somewhere else, at least you can say that you attempted to settle.