The medical device disclosed here is configured to remove a plurality of objects at a time from an interior of a living body by restricting the objects from dropping out from an interior of a basket and is capable of treating objects in a body tissues having different structures efficiently with the same device. A treatment portion of a medical device includes an outer basket and an inner basket. A plurality of outer leg portions of the outer basket and a plurality of inner leg portions of the inner basket are arranged so as to be staggered in a circumferential direction. The medical device may be used by being switched between a mode of using only the outer basket and a mode of using both of the outer basket and the inner basket.