Refer to sec. 2 of the Maternity Benefit Act, 1961, which will clarify your doubt.
Application of Act:
(1) It applies, in the first instance -
(a) to every establishment being a factory, mine, or plantation, including any such establishment belonging to the government and to every establishment wherein persons are employed for the exhibition of equestrian, acrobatic, and other performances;
(b) to every shop or establishment within the meaning of any law for the time being in force in relation to shops and establishments in a State, in which ten or more persons are employed, or were employed, on any day of the preceding twelve months:
PROVIDED that the State Government may, with the approval of the Central Government, after giving not less than two months' notice of its intention of so doing, by notification in the Official Gazette, declare that all or any of the provisions of this Act shall apply also to any other establishment or class of establishments, industrial, commercial, agricultural, or otherwise.