To provide a vacuum heat-treatment apparatus which can move workpieces from one treatment cell to other treatment cell out of several treatment cells in a short time, and can install additional treatment cells without increasing installation sites.

The vacuum heat-treatment apparatus 1 is characterized by arranging an airtight chamber 2, a transport mechanism 51 placed therein, and each treatment call of an airtight heating chambers 4 and 6, a gas cooling chamber 8, a preparatory chamber 10, and an airtight oil hardening chamber 12, on a perimeter of the airtight chamber 2. At least either one of the airtight chamber 2 and the treatment cells 4, 6, 8, and 10, can be arranged in two or more columns like in the top and the bottom. The article to be treated, which has been heated in the airtight heating chambers 4 and 6, is transported to the gas cooling chamber 8 or the airtight oil hardening chamber 12, by the transport mechanism 51 in a short time, and is hardened there. The article in any treatment cell can be transported in a short time in order to be quenched. When installing the additional cells to the apparatus, they can be installed so as to form several columns on the perimeter of the airtight chamber 2, to save the spaces.