PURPOSE: To provide a milk-pasteurizing device capable of equally thermally insulating and pasteurizing milk, reducing the number of valves and easily equally washing and pasteurizing the milk.

CONSTITUTION: Milk is delivered into a balance tank 2 through a multiplate 1. The milk is delivered from a sanitary pump 3 into the hot water-heating part 5b of a heat exchanger 5 through a flow passageway 4a and preliminarily heated in the part 5b. The pre-heated milk is delivered to the steam-heating part 5a of the heat exchanger 5 through a homogenizer 11, and again heated to 65°C there. The milk is allowed to pass through the flow passageway 4d of a holding tube unit 12, and held to 65°C during the passage to pasteurize the milk at the low temperature. The milk is delivered from a vane pump 14 into the underground cooling part 5c and the chilled water-cooling part 5d of the heat exchanger 5 through a low passageway 4e, and cooled to approximately 5°C. The treated milk is further delivered to a surge tank 15 through a flow passageway 4f and stored in the tank.