To allow easy construction work even in the case of dry construction and even where an under-girder space such as under a bridge is limited, to reduce the period of the construction work by increasing the speed of the construction work, to ensure convertibility, and to eliminate much limitations on water depth.

A plurality of split steel shells 7 are disposed around and away from a bridge pier 1, and the steel shell halves 7a, 7b are butt joined end-to-end. Water stop rubber 15 provided at the lower end of each steel shell 7 is pressed on a footing, and each steel shell 7 is positioned by a positioning member fixed on the footing of the bridge pier 1. Thereafter, water in an inner space between the bridge pier 1 and the steel shells 7 is drained.