A motor controller comprising a plurality of control systems (31, 32) configured to control actuation of a motor including windings (26, 27) of a plurality of systems, wherein: the control systems (31, 32) each include a drive circuit (311, 321) configured to supply current to a corresponding winding (26, 27) and a calculation unit (310, 320) combined with the drive circuit (311, 321); the calculation unit (310, 320) of each of the control systems (31, 32) is connected to an independent rotation angle sensor (52, 53) that detects a rotation angle of the motor; the calculation units (310, 320) include a master calculation unit and a slave calculation unit; the master calculation unit is configured to calculate a current instruction value as a target of a current amount supplied to each of the windings (26, 27) and output a detection result of the rotation angle sensor connected to the master calculation unit, together with the current instruction value, to the slave calculation unit; the master calculation unit and the slave calculation unit are each configured to control actuation of the corresponding drive circuit (311, 321) based on the current instruction value and the detection result of the rotation angle sensor connected to the master calculation unit; and when an abnormality is included in the detection result of the rotation angle sensor connected to the master calculation unit, the master calculation unit and the slave calculation unit are each configured to use a detection result of the rotation angle sensor connected to the slave calculation unit instead of the detection result of the rotation angle sensor connected to the master calculation unit to control the actuation of the corresponding drive circuit (311, 321). the control systems (31, 32) each include a drive circuit (311, 321) configured to supply current to a corresponding winding (26, 27) and a calculation unit (310, 320) combined with the drive circuit (311, 321); the calculation unit (310, 320) of each of the control systems (31, 32) is connected to an independent rotation angle sensor (52, 53) that detects a rotation angle of the motor; the calculation units (310, 320) include a master calculation unit and a slave calculation unit; the master calculation unit is configured to calculate a current instruction value as a target of a current amount supplied to each of the windings (26, 27) and output a detection result of the rotation angle sensor connected to the master calculation unit, together with the current instruction value, to the slave calculation unit; the master calculation unit and the slave calculation unit are each configured to control actuation of the corresponding drive circuit (311, 321) based on the current instruction value and the detection result of the rotation angle sensor connected to the master calculation unit; and when an abnormality is included in the detection result of the rotation angle sensor connected to the master calculation unit, the master calculation unit and the slave calculation unit are each configured to use a detection result of the rotation angle sensor connected to the slave calculation unit instead of the detection result of the rotation angle sensor connected to the master calculation unit to control the actuation of the corresponding drive circuit (311, 321).