A catheter assembly (10A) includes a catheter (16), a catheter hub (18) fixed to the catheter (16), an inner needle (12) inserted into the catheter (16), a housing (14) fixed to the inner needle (12), a guide wire (22) inserted into the inner needle (12), a guide wire hub (24) configured to support the guide wire (22), and a movement mechanism (92A) . The movement mechanism (92A) retracts the guide wire hub (24) with respect to the housing (14) such that a distal end of the guide wire (22) is housed in the inner needle (12) in association with forward movement of the catheter hub (18) with respect to the housing (14) .
