Abstract: There is provided a constant-volume dispenser which allows easy and reliable air removal from a syringe. A constant-volume dispensing syringe 10 includes a syringe 12 and a constant-volume dispenser 14. The constant-volume dispenser 14 includes an outer cylinder 26 which extends in the Arrow A direction; an inner cylinder 28 and a spring 30 which are housed in the outer cylinder 26; and a lid member 32 which is fitted to the outer cylinder 26; a pusher 34 which penetrates the outer cylinder 26, the inner cylinder 28 and the lid member 32; and an operation member 36 which, is attached to the outer cylinder 26. in a preparation operation, the operation member 36 is moved from an initial position to a stopping position whereas in operations after the preparation operation, the operation member 36 is moved from a stand-by position to the stopping position.