A catheter assembly (10A, 10B) includes a catheter (12), a catheter hub (14) fixed to a proximal end portion of the catheter (12), a hollow inner needle (16) detachably inserted in to the catheter (12), a pressing member (18, 59) capable of pressing a portion between a proximal end and a distal end of the catheter (12), a guide wire (20) slidably inserted into the inner needle (16), and a wire operating member (22, 60) which can be displaced in a longitudinal direction relative to the inner needle (16) and the catheter (12) and is connected to the guide wire (20).
