A medical device is provided. The medical device includes a puncture needle that is inserted into body tissue from outside a body and pierces membranous tissue near pulsating tissue inside the body tissue; a tubular protection member that is disposed on the outer side of the puncture needle; a pulse-information acquisition portion that acquires pulse information of the pulsating tissue; and a driving unit that moves the puncture needle and the protection member relative to each other in synchronization with the pulse information of the pulsating tissue acquired by the pulse-information acquisition portion, in such a manner that a tip of the puncture needle is retracted toward a proximal end from a distal end of the protection member when the pulsating tissue expands and that the tip of the puncture needle is projected farther forward from the distal end of the protection member when the pulsating tissue contracts.