A biopsy needle device constructed in a manner such that an internal needle is triggered in response to unlocking operation of internal needle locking device, after which a piston is retracted by a piston retraction spring in response to unlocking operation of piston locking device, whereby negative pressure is generated in a recess of the internal needle resulting in suction of biological tissue into the recess, and an external needle is triggered in response to unlocking operation of external needle locking device, thereby cutting and sampling the biological tissue which has been drawn into the recess.