An abnormality detection apparatus for resolver comprising a first system and a second system, the abnormality detection apparatus comprising: a resolver that is provided with a first system excitation winding , two first system output windings , a second system excitation winding , and two second system output windings ; a first system excitation unit configured to apply AC voltage (VRA) of a first period (TA) to the first system excitation winding ; a second system excitation unit configured to apply AC voltage (VRB) of a second period (TB) different from the first period (TA) to the second system excitation winding , wherein magnetic interference occurs between the first system and the second system due to the application of voltage to the first system excitation winding and the second system excitation winding ; a first system output signal detection unit configured to detect output signals (V1A_S, V2A_S) of the two first system output windings at a period less than or equal to half of the first period (TA); a first system reduction processing unit configured to perform a second period component reduction processing which reduces component of the second period (TB), to detection values of the output signals (V1A_S, V2A_S) of the two first system output windings ; a first system DC extraction processing unit configured to calculate DC values (V1A_DC, V2A_DC) of the two first system output signals (V1A_S, V2A_S), by performing a DC extraction processing which reduces component of the first period (TA), to the detection values (V1A_F, V2A_F) of the output signals of the two first system output windings after the second period component reduction processing; and a first system abnormality detection unit configured to determine abnormality of first system, based on whether or not the DC values (V1A_DC, V2A_DC) of the two first system output signals (V1A_S, V2A_S) are within a preliminarily set normal range of the first system. a resolver that is provided with a first system excitation winding , two first system output windings , a second system excitation winding , and two second system output windings ; a first system excitation unit configured to apply AC voltage (VRA) of a first period (TA) to the first system excitation winding ; a second system excitation unit configured to apply AC voltage (VRB) of a second period (TB) different from the first period (TA) to the second system excitation winding , wherein magnetic interference occurs between the first system and the second system due to the application of voltage to the first system excitation winding and the second system excitation winding ; a first system output signal detection unit configured to detect output signals (V1A_S, V2A_S) of the two first system output windings at a period less than or equal to half of the first period (TA); a first system reduction processing unit configured to perform a second period component reduction processing which reduces component of the second period (TB), to detection values of the output signals (V1A_S, V2A_S) of the two first system output windings ; a first system DC extraction processing unit configured to calculate DC values (V1A_DC, V2A_DC) of the two first system output signals (V1A_S, V2A_S), by performing a DC extraction processing which reduces component of the first period (TA), to the detection values (V1A_F, V2A_F) of the output signals of the two first system output windings after the second period component reduction processing; and a first system abnormality detection unit configured to determine abnormality of first system, based on whether or not the DC values (V1A_DC, V2A_DC) of the two first system output signals (V1A_S, V2A_S) are within a preliminarily set normal range of the first system. <EOS>