A device for saving bathroom water comprises a main body (1) extending along an arc, and increasing in thickness from a front portion to a back portion of the main body (1). A ramp is formed on a surface of an upper end, and a drainage hole (12) is disposed thereon. A water tank is disposed in the main body (1) and used to store water. When taking a shower, a user can stand in front of the main body, water runs off the user, falls onto the surface of the upper end of the main body, and then enters the water tank for collection. When washing floors or flushing a toilet, a user can reuse the water taken out from the water tank, reducing water wastage.