A medical device to be inserted into a blood vessel for effectively removing an object flowing in a biological lumen while reducing the burden on the living body includes an elongated shaft portion, and an expansion portion which is an elastically deformable cylindrical body having a plurality of gaps and in which a proximal portion or a distal portion of the cylindrical body is interlocked with the shaft portion. The expansion portion has a ring-shaped or annular bent portion which protrudes toward a proximal side position radially outside the expansion portion in a bent state of being bent along an axial direction, and an axial length of a second portion from the bent portion to a proximal end of the expansion portion is shorter than an axial length of a first portion from the bent portion to the distal end of the expansion portion.