A medical device includes: an elongate outer sheath； an inside shaft portion extending through an inside of the outer sheath to protrude distally beyond the outer sheath； a heating portion located between a distal portion of the outer sheath and a distal portion of the inside shaft portion, the heating portion provided with a plurality of linear material portions extending in an axial direction of the inside shaft portion； and leads electrically connected to the heating portion for passing a current to the heating portion. The linear material portion includes a conduction portion and a coating portion covering the linear material portion. The heating portion can be expanded by moving the inside shaft portion in the axial direction relative to the outer sheath. The temperature of the heating portion rises owing to electric resistance when a current flows through the heating portion.
