Retrograde analysis is a representative game analysis method that initially lists all legal positions and searches for the best move by analyzing from the final positions to the initial position. This method is effective for analyzing the games where the same position appears multiple times during sequential analysis from the initial position. However, it also has the drawback of requiring a huge amount of memory to enumerate the legal solutions. In this paper, we focus on the board game "Quoridor" released by Gigamic.