A medical device including: a needle that has an inner hole formed so as to penetrate the needle from a distal end to a base end in the longitudinal direction a medical-fluid supplying section that is connected to the base end of the needle and that supplies, to the inner hole, a medical fluid that hardens when warmed or cooled a temperature changing member that is provided at the distal end of the needle or in the vicinity of the distal end thereof and that can be warmed or cooled when supplied with energy and a temperature adjusting section that warms or cools the temperature changing member by supplying the energy to the temperature changing member.
