The present invention provides an electric syringe capable of using two types of cartridges containing dental anesthetic liquid, of which the cartridge holder is constituted in a manner capable of being equipped with 1.0 ml and 1.8 ml anesthetic liquid cartridges, and the pushing rod with the required length used for pushing the rubber plunger stopper of 1.0 ml cassette can also be used for pushing the rubber plunger stopper of 1.8 ml cassette. The cassette holder (4) used for the electric syringe capable of using two types of cartridges containing dental anesthetic liquid can be shared for the cartridge holder for both 1.0 ml cartridge (3b) and 1.8 ml cartridge (3a). The pushing rod (6) is moved in a manner capable of stopping at a common position of 1.0 ml cartridge and 1.8 ml cartridge, which has a set position for 1.0 cassette and a set position for 1.8 cassette retracted therefrom and comprises a sleeve (22) with a bottom and a restoring spring (23), wherein the sleeve is used for accommodating the rear end portion of the pushing rod pushed back from the aforementioned end position when located at the set position of 1.0 ml cartridge, the pushing rod is not interfered by the rear end thereof when the pushing rod is pushed back to the set position of 1.8 ml cartridge, the rear end of the pushing rod pushes the sleeve backward and the restoring spring is used for making the sleeve move forward along with the pushing rod while the pushing rod is moving forward.本發明是在於提供一種使卡匣保持器以可以共用於裝有1.0ml及1.8ml麻醉液卡匣之方式而構成,且利用推壓1.0ml卡匣之柱塞橡膠栓所必要之長度的推壓棒,也可以用來推壓1.8ml卡匣之柱塞橡膠栓之可兼用二種裝有牙科用麻醉液之卡匣的電動注射器。將可兼用二種裝有牙科用麻醉液之卡匣的電動注射器所使用的卡匣保持器(4),作為可共用於1.0ml卡匣(3b)及1.8ml卡匣(3a)的卡匣保持器;推壓棒(6),係以使推壓棒之移動,可在1.0ml卡匣及1.8ml卡匣所共通的位置處終止之方式地具有:1.0ml卡匣的設定位置以及從該位置縮入之1.8ml的卡匣設定位置;並包含有底的套筒(22)與復位彈簧(23),該套筒,是用以接納從上述終端位置被壓回之推壓棒的後端部分,且當推壓棒位於1.0ml卡匣的設定位置時,不會受到推壓棒的後端面所干涉,當推壓棒被壓回1.8ml的卡匣設定位置時,以推壓棒的後端面將上述套筒朝向後方推壓;該復位彈簧,是用以在推壓棒前進移動時使套筒與推壓棒一起朝向前方移動。1...電動注射器2...注射器本體3...麻醉液充填卡匣3b...1.0ml卡匣4...卡匣保持器4a、4b...視窗4’...後端面5...連結接
