Patent ID: 7056301

Claim:
A syringe adapted to mount a needle member thereon, comprising: a barrel having a barrel body in which a chamber is formed, a stop portion formed on said barrel body adjacent to said needle member, a lock portion formed on a wall of said chamber and a needle mount to be connected to said needle member, a plunger having a plunger rod, a lock device provided at a forward end of said plunger rod and an operation portion at a rear end of said plunger rod for operation by fingers; a stopper having a stopper body, which is a round disk to be squeezed into said chamber of said barrel for movement, a lock flange formed on said stopper body to be elastically deformed and to be moved forward to pass said lock portion of said barrel and to be locked by said lock portion while it is moved backward and a lock device provided to said stopper body to be connected to said lock device of said plunger that connects said stopper to said plunger to move together, wherein while said plunger is drawn, said lock device of said plunger or said lock device of said stopper is able to be broken to disengage the plunger rod from the stopper, and said stopper is received and restricted in said barrel to prevent said syringe from reuse and wherein said stopper further has a balancer connected to said stopper body, which is flexible to be compressed for deformation, and a circular balance flange pressing said wall of said chamber of said barrel.