A filter device (10) has a catheter (11) having a lumen (20), a shaft (12) extended in the longitudinal direction from the lumen (20), and a filter (13) capturing an embolus. The filter (13) is connected to the shaft (12) through a slide ring (23) at the distal end thereof. The shaft (12) is inserted into and passed through the ring (23). The ring (23) is rotatable with respect to the shaft (12) and slidable in the longitudinal direction. When the filter (13) is expanded in a blood vessel (30), the ring (23) slides on the shaft (12). The filter (13) is connected to the shaft (12) through another ring (24) on the peripheral edge of an opening (21). The shaft (12) is inserted into and passed through the ring (24). The ring (24) is rotatable with respect to the shaft (12). The ring (24) is held between a pair of stoppers (25, 26) fixed onto the shaft (12). Therefore, the movement of the ring (24) in the longitudinal direction with respect to the shaft (12) is prevented.
