To provide an immersion method for caisson with extremely excellent workability that cannot only reduce peripheral surface friction, but also bring a caisson into contact with a foundation as before without the need to completely replace a skid with a cured material, and can exhibit peripheral surface frictional force equal to or larger than that of the current foundation.

There is provided the immersion method for caisson that immerses a caisson 1 in a foundation 2, the method includes making the caisson 1 sink while injecting a konjak-like filler between the foundation 2 and caisson 1 using an injection pipe 4; then injecting a grout material from the injection pipe 4 and mixing it with the konjak-like filler; and bringing a mixture 3 of the konjak-like filler and the grout material, the caisson 1, and the foundation 2 into contact with one another.