DRAIN PIT

PROBLEM TO BE SOLVED: To suppress proliferation of bacteria or the like, make it sanitary and easily perform cleaning by making residue in drain difficult to be stored on the bottom part of a drain pit. SOLUTION: A corner part forming rectangular box whose upper part is opened in the vertical direction of the box is made a cross section arc. In addition, a cross section U-shaped invert 4 is formed on the center line of the bottom part of a drain pit 1 in a state where it is inclined in the continuous direction. The inclination lower side of the invert 4 penetrates the side of the drain pit 1, and communicates with a drain opening projected and formed from the drain pit 1. The bottom face of the drain pit 1 is formed in a state where it is downward inclined toward the invert 4. A refuse gathering cage 6 can be inserted in the drain pit.