To provide a structure of a lumber girder on foundation capable of supporting a floor board on the lumber girder on foundation at a proper height position without obstructing underfloor ventilation and fixing an end of the floor board on the lumber girder on foundation by screwing a screw into it while keeping sufficient strength of the lumber girder on foundation irrespective of small dimension of distance between a position of lower face height of the floor board and a position of upper face height of the foundation.

In this structure of the lumber girder on foundation, an anchor bolt 2 is erected on an upper face of concrete continuous footing 1, a receiving member 4 is attached to a bolt to adjust its height position, the lumber girder 6 on foundation is supported on the receiving member in the direction in which the foundation is extended, and a passage 7 for underfloor ventilation is formed between the lumber girder and the upper face of continuous footing. In this lumber girder 6, its upper wall has sufficient thickness for screwing a screw, its lower wall and right and left walls have thicknesses exceeding it, and the end of the floor board 12 is supported on the lumber girder and is fixed on the upper wall of the lumber girder by a screw 13.