A medical device includes an expansion body including multiple linear bodies, a shaft portion to which a connection portion disposed on a proximal end of the expansion body is fixed, and multiple electrode assemblies each including an electrode unit and a long wiring portion including the electrode unit at the distal part thereof. The expansion body includes a recess recessed radially inward. The recess includes a bottom, a proximal-side upright portion, and a distal-side upright portion. The electrode unit is disposed along the proximal-side upright portion or the distal-side upright portion. The shaft portion includes a distal extension portion extending from the connection portion to a distal side. A distal covering portion for bundling the multiple wiring portions of the multiple electrode assemblies on the outer surface of the distal extension portion is provided between the connection portion and a distal end of the distal extension portion.