It is an object of this disclosure to facilitate a series of puncture-related operations in a puncture instrument. In a main case of a puncture instrument, a main rod is provided. An injector rod is mounted to a main rod and includes a lancet holder on one end side. An actuating rod is mounted to the injector rod and has an engagement component on the other end side. A first biasing member biases the injector rod toward the first end side. A manipulation component is provided so as to be slidable in and out through an opening on the other end side of the main case. A locking member is axially supported rotatably by a portion of the main rod between the manipulation component and the injector rod. The locking member includes a first engaged part, a second engaged part and a second biasing member.
