A fish bowl cleaner is provided to enable a user to check the process by which water is filtered and to notify the user of the fact when the water cannot be discharged from a filter. Two filters(40,40a) are installed dually on the upper side of a pump inside a body(30) of a fish bowl cleaner to filter the water of the fish bowl twice. The water filtered at the filters are discharged to the fish bowl through the pump(60). An outlet(34) for discharging water to the outside is installed on the body which is on a position higher than the pump. A see-through window(31a) for checking the inside and a lighting device(31b) for lighting the inside are installed on a cover(31) covering the body. A sensing device(31c) for driving a warning device is installed on the upper parts of the filters.
