A catheter assembly includes a catheter； a catheter hub fixed to a proximal end portion of the catheter； a hollow needle having a needle tip and disengageably located in the catheter； a needle hub fixed to a proximal end portion of the needle； a guide wire slidably located in the needle, the guide wire being longer than the catheter and having a distal end that is protrudable from the needle tip； a guide wire hub configured to support the guide wire and move the guide wire with respect to the needle in association with movement of the guide wire hub； and a movement mechanism configured to retract the guide wire hub with respect to the needle hub such that the distal end of the guide wire is housed in the needle in association with forward movement of the catheter hub with respect to the needle hub.
