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 (111A, 112A), a second system excitation winding, and two second system output windings (111B, 112B); a first system excitation unit configured to apply AC voltage of a first period to the first system excitation winding; a second system excitation unit configured to apply AC voltage of a second period different from the first period 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 (111A, 112A) at a period less than or equal to half of the first period; a first system reduction processing unit configured to perform a second period component reduction processing which reduces component of the second period, to detection values of the output signals (V1A_S, V2A_S) of the two first system output windings (111A, 112A); 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, to the detection values (V1A_F, V2A_F) of the output signals of the two first system output windings (111A, 112A) 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 (111A, 112A), a second system excitation winding, and two second system output windings (111B, 112B); a first system excitation unit configured to apply AC voltage of a first period to the first system excitation winding; a second system excitation unit configured to apply AC voltage of a second period different from the first period 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 (111A, 112A) at a period less than or equal to half of the first period; a first system reduction processing unit configured to perform a second period component reduction processing which reduces component of the second period, to detection values of the output signals (V1A_S, V2A_S) of the two first system output windings (111A, 112A); 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, to the detection values (V1A_F, V2A_F) of the output signals of the two first system output windings (111A, 112A) 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.