To provide a sandbag which can be easily carried, and the pile of which hardly collapses when the sandbags are piled high.

The sandbag comprises a bag part 10 having a water-permeable property in which a water absorption polymer is accommodated, and at least a pair of extension pieces 11 provided in a state of being opposite to each other in the outer circumference of the bag part 10. The bag part 10 is substantially rectangular in a plan view, and the extension pieces 11 are provided on a pair of opposite sides. The bag part 10 is substantially rectangular in a planar view, and the extension pieces 11 are provided on a pair of two opposite sides. The length of the extension piece 11 is 20 cm or longer. The water absorption polymer is stored in an inner bag 2 provided in the bag part 10, and the inner bag 2 is positioned to the bag part 10. In the inner bag 2, the water absorption polymer is not discharged to the outside, and moisture is permitted to reach the inside water absorption polymer.