The overflow device for the tank which can prevent the adverse effect with the suction sound of the overflow pipe is offered. The overflow device for the tank of this invention, stand facilities is done in the storage of water section 52 which stores the water W inside the tank and storage of water section 52, at the same time the bottom open part is opened underneath the bottom wall of storage of water section, 52 flowing the water W which is stored in storage of water section 52 from the top open part, is provided in the overflow pipe 54 which note it makes come out, from the bottom open part and storage of water section 52 the sound insulation cover 47 which at the same time blocks water section all of overflow pipe 54 and, has.オーバーフローパイプの吸込音による悪影響を防止できる水槽用オーバーフロー装置を提供する。本発明の水槽用オーバーフロー装置は、水槽内の水Wを貯留する貯水部52と、貯水部52に立設され、かつ下端開口部が貯水部52の底壁下側に開放されて、貯水部52に貯留された水Wを上端開口部から流入させて下端開口部から注出させるオーバーフローパイプ54と、貯水部52に設けられ、かつオーバーフローパイプ54の水上部全域を閉塞する遮音カバー47と、を備える。
