To provide a sandbag, which has fast water swelling velocity, in which contents in the case of a swelling are not leaked and the operation of which can be prepared rapidly.

The sandbag 1 is composed of an outer bag 2 having water conveyance properties and an inner bag 3 housed in the outer bag 2. The inner bag 3 is formed of a water-soluble or water-decomposable material, and contents 4 composed of bentonite together with a water swelling/absorbing resin are housed in the inside. The sandbag consists of the outer bag having water conveyance properties and the inner bag housed in the outer bag, the inner bag is formed of the water-soluble or water-decomposable material, and the contents composed of water-absorption cellulose powder together with the water swelling/ absorpting resin are housed in the inside.