PROBLEM TO BE SOLVED: To provide a cool/warm device for pet, the device that reduces impact more than before on a pet resting on a mat caused by sound and vibration generated by a temperature controller and improves the degree of freedom of the layout in which the mat is arranged more than the conventional one.SOLUTION: The cool/warm device for a pet includes: a cool/warm mat 10 on which a pet rests; and a cool/warm control unit 20 which makes a liquid adjusted to a target temperature flow into the cool/warm mat 10. In this device, the cool/warm mat 10 and the cool/warm control unit 20 are separated and, with a liquid flowing passages 30, 40 which are formed with a flexible material, the cool/warm control unit 20 and the cool/warm mat 10 are connected.SELECTED DRAWING: Figure 1