To provide a floor temperature detection device smoothly and positively transferring heat from a floor surface to a temperature detector upon a test run of a hot water heating device.

The floor temperature detection device includes a heat insulating material 9, the temperature detector 10 provided on a lower surface side of the heat insulating material 9, and a heat transfer material 11 having thermal conductivity and covering a lower surface of the heat insulating material 9 and a lower side of the temperature detector 10. A recessed part 12 corresponding to an outline of the temperature detector 10 is provided in the heat insulating material 9. The temperature detector 10 is housed in the recessed part 12. The heat transfer material 11 is flatly formed in at least its lower surface to transfer a floor surface temperature to the temperature detector 10.