This surgical instrument (1) is a surgical instrument (1) that performs treatment on treatment target sites and is provided with: a long tubular member (2) with a moderately long shaft； a treatment unit (6) connected to the long member (2)； and a connector (10) that detachably connects the long member (2) to the treatment unit (6). The connector (10) comprises a first rotation shaft (13) that is fixed to the long member (2) and can be connected to the treatment unit (6), and a locking unit (16) that locks the first rotation shaft (13) and the treatment unit (6).
