To prevent downstair noise by the motor-driven pump motor vibration of a bath with air bubbles.

A channel material 20 with a supporting leg 22 for mounting a bathtub is projected and extended to one side, the motor 14 of a motor-driven pump is installed through a disposing base 25 provided on it, vibration proof rubber 40, a floating base 27 and the vibration proof rubber 40 and the vibration sound of the motor 14 is absorbed by utilizing the flexibility of the channel material 20 with the supporting leg 22 as a supporting point and also by the shape of the floating base 27 and the vibration proof rubber 40, etc. Thus, downstair sound pressure level A characteristics are substantially improved and the downstair noise is dissolved.