To obtain a switching device which constitutes twin compact switching devices.

The switching device includes a casing, having a body part formed with a main bus-bar connection port on both sides and a branch circuit connection port orthogonal to the body part; a main bus-bar insulation spacer closing the main bus-bar connection port, a branch circuit insulation spacer closing the branch circuit connection port; a three-phase main bus-bar supported with the main bus-bar insulation spacer and arranged while inserting through the body part; a second fixed contact projecting from the main bus-bar to the branch circuit connection port; a three-phase movable blade support conductor supported with the branch circuit insulation spacer and extended in the second fixed contact direction; a first fixed contact grounded to the casing and arranged in the vicinity of the second fixed contact; a drive shaft supported with the tip of the three-phase movable blade support conductor; and a movable blade supported with the drive shaft and contacting with/separating from the first and second fixed contacts through the turning of the drive shaft. The respective three-phase main bus-bars are arranged on one straight line in the same distance from the drive shaft.