PURPOSE: To provide a buried panel which simplifies the construction of an indirect floor heating device and burying a seamless radiation pip which circulates a heating medium liquid.

CONSTITUTION: There are formed groves 19a to 19e in which a straight running pipe is buried and projected parts 20, 21a, 22a, 25 and 26 on which finished boards or the like are loaded in a buried panel 16 which buries a radiation pipe with hard foamed resin having a small foaming power. The projected parts 25 and 26a are provided with a side in conformity with a radiation pipe having bends. The width (w) of a groove between the projected parts 25 and 27 is made greater than that of the groove 19a and 19b. A specified number of buried panels 16, which are designed as described above, are continuously installed to an area to which a floor heating device is to be installed where seamless radiation pipes are buried in the grooves. Only one end of the feed and return radiation pipes buried in the groove 19c is to be connected to a heat exchanger device. 5 to 10% water-containing ethylene glycol is used as a heating medium liquid.