PURPOSE: To provide a gas chromatographic device capable of suppressing the back flow to a septum purge passage from an insert in a sample vaporization chamber and quantitatively injecting a sample.

CONSTITUTION: An insert 3 is provided in a vaporization chamber main body 1, a septum-purge passage 6 is connected to the upper space 7 of the insert 3, and a carrier gas passage 5 feeding the carrier gas to the upper space 7 is connected to the vaporization chamber main body 1. The upper space 7 of the insert 3 is provided with an intermediate cover 9 having a hole insertable with the needle of a syringe and a spring 10 exciting the intermediate cover 9. The tip of the needle of the syringe is inserted into the insert 3 through the hole so that the intermediate cover 9 closes the upper section of the insert 3 for vaporization.