A sample injector for chromatography 10 where air or moisture can be prevented from getting mixed in when a sample is injected is provided with a syringe 11, a syringe drive unit 13, a turret 12 in which sample vials 4 are placed, a turret drive unit 14, and a control unit 30 that controls the syringe and turret drive units 13 and 14. The configuration includes a housing 15 having a gas introduction port 15a and a gas discharge port 15b that communicate with the inner space, where the syringe 11 sucks a sample from a sample vial 4, the sucked sample is injected into the sample vaporizing chamber 23 in a chromatograph 20, and a predetermined gas is introduced through the gas introduction port 15a, and at the same time, a predetermined gas is discharged through the gas discharge port 15b when a sample is analyzed.