To provide a metal trough on which cable laying works and the maintenance such as change of the cables after cable laying works are easily done, and the danger like a cover popping by the vibration of cars can be previously prevented.

The trough comprises a metal trough body 2, which has a continuous hollow and a continuous opening 4 at the corner part T axis in its direction, a metal cover 3, which is fixed to the opening 4 and is installed continuously along the trough body 2 in the axis direction, and metal fittings 7, which fit the cover 3 to the trough body 2. A stationary flange 2e with a pin hole 2 are provided protrusively at the trough body 2, and a stationary flange 3c with a pin hole 3f are provided protrusively at the cover 3, respectively. A U clip as fixed metal piece 7 is inserted into the pin holes 2f and 3d.