To solve the problems that natural bedrocks are limited in resources and expensive and do not have fixed quality, temperature rise is slow, heat loss is large and a surface temperature is not fixed either even when heating is performed by a heating means, the generation or the like of far infrared rays and anions considered to be good for a human body is low and irregular, and the consumption of heating energy is large or the like, even while a bedrock bath is spreading.

For the bedrock, black silica laminated lumber of fixed quality and high heat conductivity for highly generating the far infrared rays and the anions, etc., considered to be good for a human body and a self temperature control type planar heating means of a stable temperature which saves energy for heating are adopted.