A syringe comprising: - a syringe barrel having an inside space to be filled with a liquid drug and an opening at its distal end; - a gasket fitted in the syringe barrel for sealing the liquid drug; - a plunger with a proximal end attached to the gasket and a distal end projecting to the distal side from the opening of the syringe barrel; - an injection needle attached to the plunger, and having a proximal portion to be brought into communication with the inside space at least when the liquid drug is to be administered; - a sleeve axially movable with respect to the injection needle between an administration position such that the injection needle projects from a distal end of the sleeve and an accommodation position such that the injection needle is accommodated in the sleeve, and including a finger hook flange provided on an axially middle portion thereof; and - a coil spring provided between the sleeve and the syringe barrel for biasing the sleeve toward the accommodation position; - wherein, when the liquid drug is to be administered, the plunger is axially engaged with the sleeve at the administration position, and the syringe barrel projects from the sleeve to a proximal side; - wherein, by pushing the syringe barrel to a distal side with respect to the sleeve, the volume of the inside space is reduced so that the liquid drug flows out through the injection needle for administration thereof; - wherein, when the sleeve is moved to the accommodation position by a biasing force of the coil spring, the sleeve is axially engaged with the syringe barrel to be locked at the accommodation position, characterized in that the syringe further comprising a spring holder axially engaging to the sleeve so as to hold the coil spring in a compressed state between the sleeve and the spring holder whereby the sleeve is axially movable with respect to the injection needle and to release the engagement by further pushing the syringe barrel to the distal side after completion of the administration of the liquid drug, wherein the pushing force acts on the spring holder via the gasket, the plunger and a safety cover of the sleeve, whereby the safety cover is forcibly pushed to the distal side with respect to a main body of the sleeve to break the connection portions of lock pieces of the spring holder, wherein when the pushing of the syringe barrel is stopped, a ring portion of the spring holder is moved to the proximal side with respect to the main body by the biasing force of the coil spring. - a syringe barrel having an inside space to be filled with a liquid drug and an opening at its distal end; - a gasket fitted in the syringe barrel for sealing the liquid drug; - a plunger with a proximal end attached to the gasket and a distal end projecting to the distal side from the opening of the syringe barrel; - an injection needle attached to the plunger, and having a proximal portion to be brought into communication with the inside space at least when the liquid drug is to be administered; - a sleeve axially movable with respect to the injection needle between an administration position such that the injection needle projects from a distal end of the sleeve and an accommodation position such that the injection needle is accommodated in the sleeve, and including a finger hook flange provided on an axially middle portion thereof; and - a coil spring provided between the sleeve and the syringe barrel for biasing the sleeve toward the accommodation position; - wherein, when the liquid drug is to be administered, the plunger is axially engaged with the sleeve at the administration position, and the syringe barrel projects from the sleeve to a proximal side; - wherein, by pushing the syringe barrel to a distal side with respect to the sleeve, the volume of the inside space is reduced so that the liquid drug flows out through the injection needle for administration thereof; - wherein, when the sleeve is moved to the accommodation position by a biasing force of the coil spring, the sleeve is axially engaged with the syringe barrel to be locked at the accommodation position,