A stylet is provided which makes it possible to improve the handling of a catheter while also facilitating insertion of the catheter. A catheter set having such a stylet is also provided. A stylet with a hole and a stylet without a hole include, respectively: a stylet main body; an engaging part; a film-like linking part for linking the stylet main body and the engaging part; and a soft tip end part which is provided at a tip end of the engaging part. The engaging part has a tapered tubular shape which can expand and contract thanks to an alternating arrangement of soft parts and rigid parts in the peripheral direction. The stylet main body is then pulled rearwards from a state in which the stylet with a hole and the stylet without a hole are assembled with a catheter, thereby enabling the engaging part, which can engage with the edge of the opening of the catheter, to contract in the radial direction and be withdrawn.