PURPOSE: To prevent a filter medium from leaning to one side in a filter tank by providing a uniform dropping means for water to be filtered in a dropping opening component space of a filter device provided with a dropping opening component for switching over the water to be filtered from the horizontal direction to the converted direction and introducing the same into the filter tank on a sealing section of the filter tank.

CONSTITUTION: An expansion chamber 21 is provided on a curved section of a dropping opening component 20 for switching over water to be filtered flowing from a circulating line 3 from the horizontal direction to the vertical direction, for example, of a bathtub filter device for average homes. Further, a drawing passage 23 drawn into approximately the passage section area of a recycling 3 is formed on the outer peripheral side of a baffle 22a by the baffle 22a of a core component 22 on the downstream of said expansion chamber. Water volume, speed and uneven water pressure in the passing section area of water to be filtered generated by the sudden direction change to the vertical direction when the water to be filtered comes into a dropping component 20 are corrected by said constitution. Thus, the influence of the water to be filtered dropping into a filter tank 4 to a filter medium 8 is uniformized to prevent the filter medium 8 from leaning to one side in the filter tank 4.