PURPOSE: To simply attach a bathtub water purifying device to the peripheral edge of the bathtub of a narrow bathroom.

CONSTITUTION: In a bathtub water purifying tank to be attached to the peripheral edge of the bathtub of a bathroom, an L-shape fixing jig 8 is attached to the wall surface of the bathroom and a fixing shaft 9 is fixed to the leading end of the L-shape fixing jig 8 in an upwardly extended state. A fixing pipe 10 is attached to the frame body 2 of the purifying device to be externally fitted to the fixing shaft 9 and clamped by the nut 11 applied to the upper part of the fixing shaft 9. As a result, the fixing pipe 10 can be fixed between the L-shape fixing jig 8 and the nut 11 and the purifying device can be attached to the peripheral edge of the bathtub 1 of the bathroom.