To provide a repair reinforcement method of the existing quaywall capable of shortening a quaywall occupation period of time as much as possible, optionally setting an interlocking position of the existing sheet pile bulkhead according to conditions and effectively obtaining sufficient bending moment-proof strength and its repair reinforcement structure.

In the repair reinforcement method of the existing quaywall formed by supporting the sheet pile bulkhead 2 by a strut work 6 through a tie material 4, it has a steel pipe standing process standing a plurality of steel pipes 20 up to a predetermined depth at appropriate intervals in the vicinity thereof along the existing strut work 6, a boring machine 24 is installed in a position having a predetermined height inside of each standing steel pipe 20 to form a boring hole toward the existing sheet pile bulkhead 2 from the inside of the steel pipe 20, at the same time, a tie material installation process attaching both ends of the tie material 26 respectively to the steel pipe 20 and the existing sheet pile bulkhead 2 by inserting and installing a new tie material 26 in the boring hole from the steel pipe 20 side and a concrete filling process filling the inside of the steel pipe 20 with concrete 22 after the new tie material 26 has been attached.