To provide a sanitary equipment room floor and a construction method of the same, in which the size of the floor can be adjusted in accordance with a space where a sanitary equipment room is installed and construction work in assembling members is facilitated.

A sanitary equipment room floor A is constituted of a frame 10 arranged adjacently to a side face along the longitudinal direction of a bathtub and a floor installed on the frame 10. The frame 10 is provided with openings for work and legs 12a, 12b. The floor is constituted of side part floors 21, 22 installed on both sides in the longitudinal direction on the flame 10 and a center floor installed between the side part floors 21, 22 on the flame 10 with respective identical width between the side part floors 21, 22 and width of the center floor. Furthermore, the center floor is constituted of a drainage part floor 23 provided with a drain port and a center floor body 24.