To shorten a construction period while preventing the heaving of an excavated bottom face in excavation work for the inside of a temporary cutoff wall installed around a structure in constructing the structure such as a bridge pier.

In this construction method for preventing the heaving of the excavated bottom face generated by uplift pressure by underground water applied to the lower face 7a of an impermeable layer 7 with the descent of the excavated bottom face when excavating the inside of the temporary cutoff wall A after the installation of the temporary cutoff wall A by driving steel pipe sheet piles or steel sheet piles 1, 1, etc., in the outer periphery corresponding part of an object structure 9 as far as the impermeable layer 7, partial steel sheet piles 10, 10 of the steel pipe sheet piles or steel sheet piles 1 are driven deeper than the impermeable layer 7, and water passages 12, 12 are formed along the longitudinal inside of the steel pipe sheet piles 10, 10. Underground water deeper than the impermeable layer 7 is drained onto the excavated bottom face 8 by the water passages 12, 12.