The present invention relates to a high performance rotating electrical machine which aims at downsizing, and challenges inevitable technical problems such as deterioration of efficiency η caused by copper loss and temperature rise inside the rotating electrical machine due to heat generation induced by eddy current generated in a magnetic body. Such technical problem may be solved by configuring a coreless rotating electrical machine as comprising a stator having a cylindrical coil of a laminate structure consisting of two-layer or four-layer conductive metal sheets and a lid-type mount which fixes one of end faces of the cylindrical coil, and a rotor having a cup-type mount opposingly positioned with respect to the lid-type mount, with an air gap formed by a bottom, an inner cylindrical air-channel forming body and an outer cylindrical air-channel forming body, in which the cylindrical coil is arranged as suspended, and a plurality of magnets equipped on the outer cylindrical air-channel forming body and/or the inner cylindrical air-channel forming body, the cup-type mount has intake holes leading to the second air space on the bottom and a plurality of exhaust holes leading to the air gap, positioned in a row around a circumference of the outer cylindrical air-channel forming body, close to the bottom, and/or a plurality of exhaust holes leading to the air gap, consisting of arrays in a lengthwise direction of the air gap, from the open end face to the bottom with equally spaced intervals on the circumference of the outer cylindrical air-channel forming body, wherein ambient air taken into the second air space and/or ambient air taken into the outer side of the cylindrical coil, under differential pressure generated around the rotor by rotation thereof, are configured to directly cool a plurality of the magnets exposed in the air gap and both surfaces of the cylindrical coil arranged in the air gap, and to be discharged from the exhaust holes of the rotating outer cylindrical air-channel forming body.