Dear Ankur,
Section 3 of the IDA,1947 requires every industrial establishment having employed 100 or more no of workmen on its rolls on any day during the preceding 12 months period to constitute a "Works Committee " comprising of representatives of employer and all workmen in the establishment.
Therefore, it is mandatory on the part of the employer of such an industrial establishment to comply with. Other things in this regard can be ascertained from the provisions of relevant section.