The problem addressed by the present invention is how to dramatically reduce the likelihood of failure when sampling biological tissue. The means for solving the problem is a configuration for a biopsy device (1) in which an internal needle (2) is triggered in response to an unlocking operation of an internal needle locking means (8) followed by retraction of a piston (14) by a piston retraction spring (15) in response to an unlocking operation of a piston locking means (16) whereby negative pressure is generated in a recess (2a) of the internal needle (2) biological tissue is suctioned into the recess (2a) thereafter an external needle (3) is triggered in response to an unlocking operation of an external needle locking means (9) and the biological tissue which has been drawn into the recess (2a) is cut and sampled.
