A surgical instrument (1) includes: a fluid chamber (80) to which fluid is supplied a pulsation generator (20) which produces pulsed flow by pressurizing the fluid supplied to the fluid chamber (80) an outlet channel (82) which communicates with the fluid chamber (80) through which the pulsed flow is transmitted a fluid ejection opening (93) which communicates with the outlet channel (82) through which pulse flow is ejected toward an ejection target a suction opening (96) provided in the vicinity of the fluid ejection opening (93) and a fluid suctioning unit which suctions the fluid through the suction opening (96), wherein the opening area at an outlet opening end (93b) of the fluid ejection opening (93) on the side near the ejection target is larger than the opening area at an inlet opening end (93a) of the fluid ejection opening (93) on the side near the outlet channel (82).
