A prefilled syringe comprising: a syringe barrel including a liquid-drug discharge portion on a distal end of the syringe barrel and an opening on a proximal end of the syringe barrel; a cap detachably attached to the syringe barrel to seal the liquid-drug discharge portion; a gasket inserted in the syringe barrel; a plunger including a shaft portion inserted in the syringe barrel from the opening and a pressing portion located on a proximal end of the shaft portion and configured to be manually pushed by a user, the plunger being movable toward a distal direction by pushing the pressing portion to slide the gasket toward the liquid-drug discharge portion; and a liquid-drug stored between the liquid-drug discharge portion and the gasket in the syringe barrel, the liquid-drug being dischargeable from the liquid-drug discharge portion by sliding of the gasket, the prefilled syringe comprising: an upraised portion located on an inner wall of the syringe barrel between the gasket and the opening and including a step protruding approximately perpendicular to a central axis of the syringe barrel; and a clicker protruding from a side surface of the shaft portion and configured to slide against the upraised portion along with a movement of the plunger toward the distal direction and flex inward in a direction approximately perpendicular to a central axis of the shaft portion by sliding up the upraised portion, the clicker being configured to be flipped by crossing over the upraised portion to generate a clicking sound and/or a clicking vibration at approximately a same moment as when the liquid-drug is completely discharged, wherein the clicker includes: a flexing portion branching off from the side surface of the shaft portion and having an inclined section inclined away from the central axis of the shaft portion in a natural state; and a sliding portion connected to the flexing portion and configured to slide against the upraised portion. a syringe barrel including a liquid-drug discharge portion on a distal end of the syringe barrel and an opening on a proximal end of the syringe barrel; a cap detachably attached to the syringe barrel to seal the liquid-drug discharge portion; a gasket inserted in the syringe barrel; a plunger including a shaft portion inserted in the syringe barrel from the opening and a pressing portion located on a proximal end of the shaft portion and configured to be manually pushed by a user, the plunger being movable toward a distal direction by pushing the pressing portion to slide the gasket toward the liquid-drug discharge portion; and a liquid-drug stored between the liquid-drug discharge portion and the gasket in the syringe barrel, the liquid-drug being dischargeable from the liquid-drug discharge portion by sliding of the gasket, the prefilled syringe comprising: an upraised portion located on an inner wall of the syringe barrel between the gasket and the opening and including a step protruding approximately perpendicular to a central axis of the syringe barrel; and a clicker protruding from a side surface of the shaft portion and configured to slide against the upraised portion along with a movement of the plunger toward the distal direction and flex inward in a direction approximately perpendicular to a central axis of the shaft portion by sliding up the upraised portion, the clicker being configured to be flipped by crossing over the upraised portion to generate a clicking sound and/or a clicking vibration at approximately a same moment as when the liquid-drug is completely discharged, wherein the clicker includes: a flexing portion branching off from the side surface of the shaft portion and having an inclined section inclined away from the central axis of the shaft portion in a natural state; and a sliding portion connected to the flexing portion and configured to slide against the upraised portion. an upraised portion located on an inner wall of the syringe barrel between the gasket and the opening and including a step protruding approximately perpendicular to a central axis of the syringe barrel; and a clicker protruding from a side surface of the shaft portion and configured to slide against the upraised portion along with a movement of the plunger toward the distal direction and flex inward in a direction approximately perpendicular to a central axis of the shaft portion by sliding up the upraised portion, the clicker being configured to be flipped by crossing over the upraised portion to generate a clicking sound and/or a clicking vibration at approximately a same moment as when the liquid-drug is completely discharged, wherein the clicker includes: a flexing portion branching off from the side surface of the shaft portion and having an inclined section inclined away from the central axis of the shaft portion in a natural state; and a sliding portion connected to the flexing portion and configured to slide against the upraised portion. a flexing portion branching off from the side surface of the shaft portion and having an inclined section inclined away from the central axis of the shaft portion in a natural state; and a sliding portion connected to the flexing portion and configured to slide against the upraised portion.