An electric junction box to prevent fluid such as water infiltrating inside the covers from adhering to a printed wiring board even if the upper cover and lower cover are stacked to each other in an orthogonal direction, comprises a metal board, the surface being arranged in a horizontal direction, and a main body accommodating the metal board. The main body includes an upper cover and a lower cover to be stacked to each other in a direction orthogonal to a surface of the metal board. On a side wall of the lower cover a locking projection is disposed. On a side wall of the upper cover a locking step is disposed with which the locking projection is locked. The upper cover includes an inner wall disposed inside the side wall of the lower cover, the lower end being disposed below the metal board.