PROBLEM TO BE SOLVED: To provide a syringe which can be made compact and which can easily perform a pressurizing operation and a depressurizing operation. SOLUTION: The syringe 1 has a cylindrical pressurizing syringe portion 23 formed on the distal end side, and a larger opening area than the pressurizing syringe portion 23 formed continuously on the proximal end side of the pressurizing syringe portion 23. A syringe body 2 having a cylindrical decompression syringe portion 22 having an opening area, a decompression piston 3 arranged to be able to advance and retract inside the decompression syringe portion 22, and a reciprocating inside the decompression piston 3. Is inserted into the pressurizing syringe part 23 or the insertion position which is formed by penetrating the pusher part 42 disposed in the pressure reducing piston 3 and the closing part 32 of the depressurizing piston 3 and is inserted into the pressurizing syringe part 23 so as to be able to move back and forth. A pressurizing piston 4 having a pressurizing extension part 41 movably arranged in a non-inserting position, and a pressurizing and holding mechanism for holding the position of the pressurizing piston 4 in the advancing direction with respect to the pressurizing syringe part 23. 61 is provided. [Selection diagram] Fig. 3B【課題】コンパクトに形成できると共に、加圧動作及び減圧動作を容易に行うことができるシリンジを提供すること。【解決手段】シリンジ１は、先端側に形成される筒状の加圧用シリンジ部２３と、加圧用シリンジ部２３に連続して基端側に形成され加圧用シリンジ部２３の開口面積よりも大きな開口面積を有する筒状の減圧用シリンジ部２２と、を有するシリンジ本体２と、減圧用シリンジ部２２の内部に進退可能に配置される減圧用ピストン３と、減圧用ピストン３の内部に進退可能に配置される押し子部４２と、減圧用ピストン３の閉鎖部３２を貫通して形成され加圧用シリンジ部２３の内部に進退可能に挿入される挿入位置又は加圧用シリンジ部２３の内部に挿入されない非挿入位置に移動可能に配置される加圧延出部４１と、を有する加圧用ピストン４と、加圧用シリンジ部２３に対して加圧用ピストン４の進行方向の位置を保持する加圧保持機構６１と、を備える。【選択図】図３Ｂ
