A simple mechanism that provides the manipulations required to deliver a correct injection and also incorporates the safety modifications that are needed to prevent needlestick injury and ensure self destruct capability. It is a feature that an organic piezoelectric material of the present invention possesses a compound represented by Formula and a base material made of an organic polymeric material, satisfying Expression : |C Log P \u2212C Log P |\u22663. Thereby, an acoustic power of the transmitted ultrasound can be controlled without making the transmission amplitude variable.