A fluid injection device includes: a pulse generator which converts fluid into pulse flow; a suction pipe projecting from the pulse generator; an injection pipe which is eccentrically inserted into the suction pipe such that the outer circumferential surface of the injection pipe contacts the inner circumferential surface of the suction pipe, and has an injection opening communicating with the pulse generator; and a suction channel and a suction opening formed between the inner circumferential surface of the suction pipe and the outer circumferential surface of the injection pipe, wherein the injection pipe is fixed to the inner circumferential surface of the suction pipe in the vicinity of the injection opening.