Thermostat device

A thermostat device, comprising:

• a housing that is disposed in a circulation passage for circulating coolant between an internal combustion engine and a radiator, inside which an accommodation chamber is disposed, and which includes a first conduit and a second conduit for refluxing the coolant to the accommodation chamber;
• a thermo-element that is accommodated in the accommodation chamber and configured to move in an axial direction depending on the temperature of the coolant;
• a control valve for controlling an amount of coolant reflux in the first conduit by the axial movement of the thermo-element;
• and
• a valve seat inside the housing on which the control valve abuts in a valve-closed state, wherein
• the second conduit opposes a side portion of the thermo-element, and on a direction side, to which the control valve approaches the valve seat, which is a one-end side of the direction of the movement of the thermo-element on the inner circumferential wall of the second conduit,
• a slope inclining toward the one-end side as approaching the accommodation chamber from one end of the second conduit, and
• the accommodation-chamber-side end of the slope is located toward the one-end side than relative to the position of a lower end of the valve seat.