A dual chamber prefillable syringe, comprising: a cylinder which has a cylindrical shape with an axis line as a center and has a bypass portion formed due to bulging of a part of an inner circumferential surface to the outside; a hub luer-lock which is provided at the front end of the cylinder; a finger grip which is provided at the rear end of the cylinder; a front stopper which is fitted on the front end side of the bypass portion in the cylinder; a middle stopper which is fitted on the rear end side of the bypass portion in the cylinder to seal a preparation together with the front stopper; an end stopper which is fitted on the rear end side of the middle stopper in the cylinder to seal a solvent together with the middle stopper; a plunger rod which is connected to the end stopper from the rear end side by inserting the finger grip; a female screw portion which is formed to be screwed around the axis line on an inner circumferential surface of the finger grip; and a male screw portion which is formed to be able to screw together with the female screw portion on an outer circumferential surface of the plunger rod, characterized by a guide groove which is formed in the female screw portion and extends parallel to the axis line; a guide plate which is formed on the rear end side of the male screw portion on the outer circumferential surface of the plunger rod and is guided in accordance with the guide groove; and a first protrusion which is formed at the rear end of the finger grip and with which the guide plate is arranged to be brought into contact, so as to be able to surmount thereover, when at least a part of the middle stopper, which is advanceable by rotating the plunger rod in accordance with the female screw portion and the male screw portion, moves across the bypass portion. a cylinder which has a cylindrical shape with an axis line as a center and has a bypass portion formed due to bulging of a part of an inner circumferential surface to the outside; a hub luer-lock which is provided at the front end of the cylinder; a finger grip which is provided at the rear end of the cylinder; a front stopper which is fitted on the front end side of the bypass portion in the cylinder; a middle stopper which is fitted on the rear end side of the bypass portion in the cylinder to seal a preparation together with the front stopper; an end stopper which is fitted on the rear end side of the middle stopper in the cylinder to seal a solvent together with the middle stopper; a plunger rod which is connected to the end stopper from the rear end side by inserting the finger grip; a female screw portion which is formed to be screwed around the axis line on an inner circumferential surface of the finger grip; and a male screw portion which is formed to be able to screw together with the female screw portion on an outer circumferential surface of the plunger rod, characterized by a guide groove which is formed in the female screw portion and extends parallel to the axis line; a guide plate which is formed on the rear end side of the male screw portion on the outer circumferential surface of the plunger rod and is guided in accordance with the guide groove; and a first protrusion which is formed at the rear end of the finger grip and with which the guide plate is arranged to be brought into contact, so as to be able to surmount thereover, when at least a part of the middle stopper, which is advanceable by rotating the plunger rod in accordance with the female screw portion and the male screw portion, moves across the bypass portion.