To improve safety by mounting a generator in a position wherein the view from an operator in a cab is not obstructed in construction machinery for working by attaching a magnet on a tip of an arm.

In this construction machinery, a generator unit 16 comprising the generator 15 and its peripheral mechanism component is mounted on a left side of a front part of an upper turning body 13, and the cab 17 is mounted on an upper part of the generator unit 16. The arm 20 is installed pivotally on a tip of a boom 19 mounted on the upper turning body 13 so as to be moved up and down, and the magnet 22 is suspended from a tip of the arm 20 through a chain 21. The electric power is supplied to an electromagnet 22b of the magnet 22 from the generator 15 through a cable 23.