PURPOSE: To smoothly inject a sample by driving a micro syringe of gas chromatography, which is held by a holding ring and a rotating ring, to move the micro syringe while rotating it and detecting the movement to depress a piston of the syringe.

CONSTITUTION: A micro syringe 1 in which the sample is put is fitted to an inner ring 2A and a rotating ring 3 brought into contact with a rotating roll 4. When a handle 7 is pushed in the direction of an arrow, the roll 4 is rotated through a shaft 5, a driving shaft 9, and a revolving shaft 10. Then, the ring 3, the inner ring 2A, and the cylinder 1 are rotated as one body and the syringe 1 is approximated to a needle guide 20. When it reaches a prescribed position, a projecting part 6A is brought into contact with a detecting element 13 and a solenoid 14 pushes the piston head of the syringe 1. A needle 1B of the syringe 1 is inserted to a guide 20 while being rotated and pierces a septum rubber 21 and is inserted to a glass insert 22, and the sample is automatically injected.