A filter device includes a main body portion having a cylinder shape, and the main body portion is inserted along a center axis of the pipe. One end portion of the main body portion structuring a filter device is blocked. At least one portion of a flange portion is provided between both end portions of the cylinder, and the flange portion divides a space inside the pipe in a liquid-tight state by elastically deforming and by being attached firmly to an inner surface of the pipe. A first passing portion of the liquid is provided in a cylinder side portion between the one end portion of the cylinder and the flange portion, and a second passing portion of the liquid is provided on a side close to the other end portion of the cylinder than the flange portion.