PROBLEM TO BE SOLVED: To provide a highly-reliable rotating electrical machine which is configured to prevent surface discharge from occurring in air even when a corona shield layer is eroded by occurrence of discharge in a space near an interface between the corona shield layer and an insulating layer formed on the periphery of a coil conductor. SOLUTION: The rotating electrical machine includes: a coil conductor 10 housed in an iron core slot 2 and extending to the outside of the iron core slot 2; a main ground insulation layer 4 formed on the periphery of the coil conductor 10; and a corona shield layer 7 which is provided on the outer periphery of the main ground insulation layer 4 so as to extend from the inside to the outside of the iron core slot 2 and prevents corona discharge in the iron core slot 10. In the rotating electrical machine, an electric field relaxation layer constituted by winding an electric field relaxation prepreg tape 23 or applying electric field relaxation paint is formed on the outer periphery of the corona shield layer 7 located outside the iron core slot 2, as a protective layer against surface discharge in order not to expose the corona shield layer 7. COPYRIGHT: (C)2012,JPO&INPIT