To efficiently and sufficiently perform underfloor ventilation by providing a floor load supporting implement with a ventilator under the floor surrounded by an outer wall cloth foundation and whose sleeper is supported by the implement, and ventilating.

Blocks are formed by outer wall cloth foundations 1 and cloth foundations 2 for partition bearing walls. A floor load supporting implement 3 with a ventilator has a floor load support 31 and a ventilator 32 which is direction adjustably mounted to the support 31 as main constituents. The support 31 is constituted of various type load support 31 having a pipe type turn buckle body 31a. The body 31a is preferably formed with steps so that the ventilator 32 may not slip down. As the ventilator 32, conventional various type fan driven by a motor can be used. It is preferable to mount the ventilator 31 at the body 31a adjustably in a wind direction.