To provide a hydrothermal sterilization method for a multieffect evaporator-type distilled water production system, capable of normally producing distilled water as in the past, and sterilizing a feed-water wetted part within the system with hot liquid in sterilization, by providing a simple additive means.

The multieffect evaporator-type distilled water production system includes: a preheating means of feed water; a plurality of evaporators for successively generating pure steam from the preheated feed water; a steam-water separation means for the generated pure steam; a condenser which cools the pure water subjected to steam-water separation with feed water and cooling water to make distilled water; and an outside air introduction means connected to the condenser. The system further includes a hydrothermal sterilization circulating pipe branched from the middle of a pipe connecting a preheater to a first evaporator and returned to the base end of a feed water inlet pipe is provided, so that the feed-water wetted part can be hydrothermally sterilized using the feed water heated by the preheater.