To increase the whole strength as a steel pipe sheet pile compared with a conventional steel pipe sheet pile, which results in exhibiting the cut-off effect of a closed space, reducing water quality pollution caused by cut-off works and increasing an economic effect to provide environmental countermeasures and moreover improving the shearing yield strength of a joint remarkably by enhancing the yield strength of the joint in a steel pipe sheet pile well foundation with a plurality of steel pipe sheet piles combined in closed shape while fitting joints.

The steel pipe sheet pile 1 is provided with a male joint and a female joint of wide-flange shape steel as the joints at H-steel connected type steel pipes with steel pipes 2 integrally connected to each other by tie members of wide-flange shape steel 4 whose flange edges are connected to the peripheral surface of each steel pipe 2. The wide-flange shape steel male joint 7 is rather small-sized to be fittable into a space surrounded by the flange inner side face and web face of the wide-flange shape steel female joint 8. Further, the wide-flange shape steel male joint 7 and wide-flange shape steel female joint 8 in the steel pipe pile sheet 1 are suitably angled in the projecting direction with respect to the tie members of wide-flange shape steel 4 if necessary so as to be combined in closed shape as a whole.