A medical device (1) includes a main body (2) elongated in a vertical direction, a guide section (slide section (23)) protruding from a lower end of the main body in a direction crossing the vertical direction, and including a first guide hole (235) and a second guide hole (236), a first unit (A) including a first puncture needle (4) of a hollow structure and a first holding plate (61), the first puncture needle being slidably supported by the main body near an upper end of the first puncture needle in the vertical direction and having a sharp lower end slidably inserted into the first guide hole from above, the first holding plate being integrally fixed to neighborhoods of the upper end of the first puncture needle, and a second unit (B) including a second puncture needle (3) and a second holding plate (62), the second puncture needle being slidably inserted into the second guide hole from above, the second holding plate being integrally fixed to neighborhoods of an upper end of the second puncture needle, wherein the second holding plate separably abuts on the first holding plate from above, and a position of the second guide hole is selectable along the guide section.