A catheter assembly includes an inner needle having a sharp tip at a distal end thereof； a catheter in which the inner needle is disposed； a tip protective member having an insertion hole through which the inner needle is insertable, the tip protective member being configured to cover at least a tip of the inner needle when the inner needle is withdrawn； and a shutter member which is arranged in an interior of a shutter accommodating section provided in the tip protective member, the shutter member being configured to be deformed and thereby block a movement path of the inner needle in the shutter accommodating section when the inner needle is retracted to a predetermined position relative to the tip protective member. The shutter accommodating section includes a needle guide configured to guide movement of the inner needle.
