A cooling structure for cooling a stator core of a rotating electrical machine includes: a stator core (1b) arranged along an outer periphery of a rotor fixed to a rotary shaft (AX) of a rotating electrical machine; a stator frame (2) extending along an outer peripheral surface of the stator core (1b), the stator frame being configured to fix and support the stator core from the outer peripheral surface side thereof; and a motor case (7) having small-diameter end portions on both sides in an axial direction of the rotary shaft (AX), the small-diameter end portions being welded with airtightness onto an outer peripheral surface of the stator frame so that the motor case forms a space, which is the coolant flow path (CC), together with the outer peripheral surface of the stator frame.