Is there any other law relating to obscenity in India ?

Yes, Sections 292, 293 and 294 of the Indian Penal Code. (See Appendix)

Why was it necessary to have a separate legislation to prohibit obscenity? In spite of the above provisions of the Indian Penal Code, indecent representation of women in publications, especially in advertisements, were multiplying every day. This has the effect of denigrating women. It also corrupts persons, especially the youth. So it was felt necessary to have a separate legislation to effectively prohibit the indecent reprsentation of women through advertisements, books, pamphlets etc.