A catheter assembly comprises: a catheter; a catheter hub fixed to a proximal end portion of the catheter; an inner needle disposed inside the catheter; and a housing; wherein a distal end of the housing comprises a portion configured to support the inner needle via the catheter; wherein, when the catheter assembly is in an initial state in which a distal end of the inner needle protrudes from a distal end of the catheter, the housing accommodates the catheter hub; and wherein the catheter hub is configured to rotate with respect to the inner needle and the housing when accommodated inside the housing.