PURPOSE: To provide a hose connecting mechanism having good workability and highly reliable operability, in relation to a connecting mechanism of a hose for use in a water cooling type cooling system.

CONSTITUTION: A hose connection part is composed of an inner cylinder 1 made of a shape memory alloy, the body part 2 of which is expanded in the radial direction by heating to closely contact the inner face of an inner cylinder- connecting port 21 provided on the tank 20 side, and an outer cylinder 5 made of a shape memory alloy, the inner diameter part of which is contracted in the radial direction by heating to closely contact a hose 10 connected to the inner cylinder 1.