A three-phase rotary electrical machine, comprising: a stator including a stator core including split cores split in a circumferential direction of a rotation axis; a rotor arranged coaxially with and facing the stator; first and second bobbins (30, 40) made of an insulating material and attached to each of the split cores, a winding being wound in a concentrated winding method around each split core to which the respective bobbin (30, 40) is attached, the winding being provided for each of three phases of the rotary electrical machine; a first bobbin unit being constituted by three of the first bobbins (30, 30, 30) which are arranged in the circumferential direction as one unit; and a second bobbin unit being constituted by three of the second bobbins (40, 40, 40) which are arranged in the circumferential direction as one unit; wherein each bobbin (30, 40) includes inner peripheral side end portions (34, 43), the inner peripheral side end portions (34, 43) of the bobbin (30, 40) positioned at a center among the three bobbins (30, 40) constituting the bobbin unit (50, 60) are formed in a bendable manner integrally with the corresponding inner peripheral side portion (34, 43) of each of the bobbins (30, 40) positioned adjoining to the bobbin (30, 40) positioned at the center, the bobbin unit (50, 60) is split in an axial direction of the rotation axis in such a way that the bobbin unit (50, 60) is configured to be attached to three of the split cores from axial ends of the three split cores, the three of the split cores are attached with the bobbin unit (50, 60) from the axial ends, the bobbin unit (50, 60) is sealed at the corresponding inner peripheral side end portions (34, 43) with the bobbin unit (50, 60) positioned adjoining thereto, and a cooling passage extending in the axial direction is provided at each clearance between the windings for the three phases, characterized in that a sealing member is retained in a sandwiched manner between the inner peripheral side end portions (34, 34) of the first bobbin unit and between the inner peripheral side end portions (43, 43) of the second bobbin unit. a stator including a stator core including split cores split in a circumferential direction of a rotation axis; a rotor arranged coaxially with and facing the stator; first and second bobbins (30, 40) made of an insulating material and attached to each of the split cores, a winding being wound in a concentrated winding method around each split core to which the respective bobbin (30, 40) is attached, the winding being provided for each of three phases of the rotary electrical machine; a first bobbin unit being constituted by three of the first bobbins (30, 30, 30) which are arranged in the circumferential direction as one unit; and a second bobbin unit being constituted by three of the second bobbins (40, 40, 40) which are arranged in the circumferential direction as one unit; wherein each bobbin (30, 40) includes inner peripheral side end portions (34, 43), the inner peripheral side end portions (34, 43) of the bobbin (30, 40) positioned at a center among the three bobbins (30, 40) constituting the bobbin unit (50, 60) are formed in a bendable manner integrally with the corresponding inner peripheral side portion (34, 43) of each of the bobbins (30, 40) positioned adjoining to the bobbin (30, 40) positioned at the center, the bobbin unit (50, 60) is split in an axial direction of the rotation axis in such a way that the bobbin unit (50, 60) is configured to be attached to three of the split cores from axial ends of the three split cores, the three of the split cores are attached with the bobbin unit (50, 60) from the axial ends, the bobbin unit (50, 60) is sealed at the corresponding inner peripheral side end portions (34, 43) with the bobbin unit (50, 60) positioned adjoining thereto, and a cooling passage extending in the axial direction is provided at each clearance between the windings for the three phases, characterized in that a sealing member is retained in a sandwiched manner between the inner peripheral side end portions (34, 34) of the first bobbin unit and between the inner peripheral side end portions (43, 43) of the second bobbin unit.