A medical device is disclosed for cutting an object in a body lumen, including: a rotatable drive shaft; and a rotatable rotation structure which is connected to the drive shaft, the rotation structure including: a proximal portion; a distal portion; and a constricted portion provided between the proximal portion and the distal portion, the constricted portion including: a first tapered portion which includes a first cutting portion and decreases in diameter toward the distal side; a second tapered portion which includes a second cutting portion and decreases in diameter toward the proximal side; and a bottom portion which is provided between the first tapered portion and the second tapered portion.