A rotation angle detector, comprising: a rotor, which includes N x salient poles; a stator, including teeth Ti, where i = 1 to m, circumferentially arranged, where "m" is a natural number; a first excitation winding Rai, where i=1 to m, which is mounted on an i-th tooth Ti of the stator; a second excitation winding Rbi, where i=1 to m, which is mounted on the i-th tooth Ti of the stator; a first excitation circuit and a second excitation circuit, which are configured to apply AC voltages to the first excitation winding Ral to Ram and the second excitation winding Rb1 to Rbm, which are connected in series, respectively; characterized by a first output winding Sai, where i=1 to m, which is mounted on the i-th tooth Ti of the stator; a second output winding Sbi, where i=1 to m, which is mounted on the i-th tooth Ti of the stator; a third output winding Sci, where i=1 to m, which is mounted on the i-th tooth Ti of the stator; an angle calculator, which is configured to calculate a rotation angle of the rotor from output voltages of the first output winding Sa1 to Sam, the second output winding Sb1 to Sbm, and the third output winding Sc1 to Scm, wherein, when one spatial order cycle of an output winding is defined as an electrical angle of 360°, a phase difference of an electrical angle α is provided between the first output winding and the second output winding, and between the second output winding and the third output winding, respectively, and α≠180°×n is satisfied (n is an integer), wherein each of the electrical angle phase differences α between the first output winding and the second output winding, and between the second output winding and the third output winding satisfies "α=60°±5°+180°×n (n is an integer)" or "α=120°±5°+180°×n (n is an integer)," wherein: one end of each of the first output winding, the second output winding, and the third output winding is electrically connected to construct a neutral point; the neutral point and another end of each of the first output winding, the second output winding, and the third output winding are electrically connected to the angle calculator; and the angle calculator is configured to calculate the rotation angle from two output voltages out of four output voltages obtained from the neutral point and another end of each of the first output winding, the second output winding, and the third output winding. a rotor, which includes N x salient poles; a stator, including teeth Ti, where i = 1 to m, circumferentially arranged, where "m" is a natural number; a first excitation winding Rai, where i=1 to m, which is mounted on an i-th tooth Ti of the stator; a second excitation winding Rbi, where i=1 to m, which is mounted on the i-th tooth Ti of the stator; a first excitation circuit and a second excitation circuit, which are configured to apply AC voltages to the first excitation winding Ral to Ram and the second excitation winding Rb1 to Rbm, which are connected in series, respectively; characterized by a first output winding Sai, where i=1 to m, which is mounted on the i-th tooth Ti of the stator; a second output winding Sbi, where i=1 to m, which is mounted on the i-th tooth Ti of the stator; a third output winding Sci, where i=1 to m, which is mounted on the i-th tooth Ti of the stator; an angle calculator, which is configured to calculate a rotation angle of the rotor from output voltages of the first output winding Sa1 to Sam, the second output winding Sb1 to Sbm, and the third output winding Sc1 to Scm, wherein, when one spatial order cycle of an output winding is defined as an electrical angle of 360°, a phase difference of an electrical angle α is provided between the first output winding and the second output winding, and between the second output winding and the third output winding, respectively, and α≠180°×n is satisfied (n is an integer), wherein each of the electrical angle phase differences α between the first output winding and the second output winding, and between the second output winding and the third output winding satisfies "α=60°±5°+180°×n (n is an integer)" or "α=120°±5°+180°×n (n is an integer)," wherein: one end of each of the first output winding, the second output winding, and the third output winding is electrically connected to construct a neutral point; the neutral point and another end of each of the first output winding, the second output winding, and the third output winding are electrically connected to the angle calculator; and the angle calculator is configured to calculate the rotation angle from two output voltages out of four output voltages obtained from the neutral point and another end of each of the first output winding, the second output winding, and the third output winding. one end of each of the first output winding, the second output winding, and the third output winding is electrically connected to construct a neutral point; the neutral point and another end of each of the first output winding, the second output winding, and the third output winding are electrically connected to the angle calculator; and the angle calculator is configured to calculate the rotation angle from two output voltages out of four output voltages obtained from the neutral point and another end of each of the first output winding, the second output winding, and the third output winding.