A rotor for an electric rotating machine, comprising permanent magnets embedded in a plurality of magnet insertion holes axially extending through a circumference of a cylindrical rotor core respectively, each permanent magnet embedded in the magnet insertion hole having both lengthwise ends having respective voids formed by expanding the magnet insertion holes so that the voids extend axially through the rotor core; a rotating shaft extending through a central portion of the rotor core thereby to be fixed, and a plurality of d-axis through holes provided on each d-axis corresponding to a direction of magnetic flux so as to extend in an axial direction in an outer circumferential side relative to the embedded permanent magnets, a plurality of hollow shafts (15a, 15b) formed in both axial ends of the rotating shaft not inserted into the rotor core; the hollow shafts (15a, 15b) having hollow shaft wall holes formed in hollow shaft walls of the hollow shaft at both ends of the rotating shaft so as to radially extend through the hollow shaft, respectively; and a plurality of presser plates mounted on both axial ends of the rotor core so as to hold the rotor core therebetween; a plurality of cooling grooves (30, 31) formed in faces of the presser plates in contact with the rotor core, so as to connect the hollow shaft wall hole, the d-axis through holes and the voids respectively, the cooling grooves (30, 31) including first annular grooves provided in the respective presser plates and connecting the d-axis through holes and second annular grooves provided in the respective presser plates and radial grooves provided in the respective presser plates and connecting the first and second annular grooves and the hollow shaft wall holes, wherein: the presser plates are further provided with respective presser plate refrigerant outlet holes, the presser plate refrigerant outlet holes of one of the presser plates having diameters differing from diameters of presser plate refrigerant outlet holes of the other presser plates; and a refrigerant channels which is formed so that a refrigerant supplied into one of the hollow shafts (15a, 15b) of the rotating shaft flows through the refrigerant channels and further through the hollow shaft wall hole of said one hollow shaft (15a, 15b) and the radial grooves of the respective presser plates, into a flow including the first annular grooves of the presser plates, the d-axis through holes of the rotor core and the first annular grooves of the oppositely located presser plate and into a second flow path including the second annular grooves of the presser plate, the voids of the rotor core and second annular grooves of the oppositely located presser plate, the refrigerant flowing into the radial grooves of the respective presser plates including a part thereof which is discharged through the refrigerant outlet holes of said one of the presser plates and a remaining part thereof is discharged through the refrigerant outlet holes of said other presser plates. the presser plates are further provided with respective presser plate refrigerant outlet holes, the presser plate refrigerant outlet holes of one of the presser plates having diameters differing from diameters of presser plate refrigerant outlet holes of the other presser plates; and a refrigerant channels which is formed so that a refrigerant supplied into one of the hollow shafts (15a, 15b) of the rotating shaft flows through the refrigerant channels and further through the hollow shaft wall hole of said one hollow shaft (15a, 15b) and the radial grooves of the respective presser plates, into a flow including the first annular grooves of the presser plates, the d-axis through holes of the rotor core and the first annular grooves of the oppositely located presser plate and into a second flow path including the second annular grooves of the presser plate, the voids of the rotor core and second annular grooves of the oppositely located presser plate, the refrigerant flowing into the radial grooves of the respective presser plates including a part thereof which is discharged through the refrigerant outlet holes of said one of the presser plates and a remaining part thereof is discharged through the refrigerant outlet holes of said other presser plates.