a prefilled syringe composed of a barrel having a luer tip at one end and an open proximal end , the barrel having at least a three layer structure of an innermost layer , an outermost layer , both made of a polyolefin resin , and an intermediate layer made of a resin with a barrier property and sandwiched by the innermost layer and the outermost layer . the barrel is produced through the sequential steps of : injecting a specific amount of a polyolefin resin inside a cavity ; injecting a specific amount of a resin excelling in barrier property ; injecting a specific amount of the polyolefin resin again ; and separating the luer tip surface and an injection unit by pushing off a valve pin provided inside a valve gate or an inner nozzle of the injection unit , which injects the resin excelling in barrier property , toward the direction of the luer tip surface as desired .