A motor control unit that includes a motor control signal output unit that is configured to output a motor control signal, a drive circuit that is configured to supply driving current to a motor based on the motor control signal, and an estimated motor rotation angle calculation unit that is configured to accumulate change amounts ( Δθm) of a motor rotation angle in each calculation period to calculate an estimated motor rotation angle ( θm), wherein the motor control signal output unit is configured to output the motor control signal based on the estimated motor rotation angle ( θm), the motor control unit being characterized by comprising: a rough rotational position estimation unit that is configured to estimate a rough rotational position of the motor based on a combination of a sign of an axis inductive voltage value (e α) of a first coordinate axis and a sign of an axis inductive voltage value of a second coordinate axis (e β) on a two-phase fixed coordinate system, and a magnitude relation between the axis inductive voltage value of the first coordinate axis and the axis inductive voltage value of the second coordinate axis, wherein the rough rotational position estimation unit is configured to estimate in which of eight regions, obtained by dividing the plane of coordinates into eight regions at intervals of 45° in electric angle, the motor rotation angle is located; and a rotation direction estimation unit that is configured to estimate a rotation direction of the motor based on a change in the rough rotational position, estimated by the rough rotational position estimation unit, wherein the estimated motor rotation angle calculation unit is configured to determine a sign of the change amount ( Δθm) based on the rotation direction of the motor, estimated by the rotation direction estimation unit, wherein the estimated motor rotation angle calculation unit is configured to accumulate change amounts ( Δθm) of the motor rotation angle in each calculation period to calculate an estimated motor rotation angle ( θm) by adding or subtracting, based on the determined sign of the change amount, the change amount to a value of the motor rotation angle in an immediately preceding calculation period. a rough rotational position estimation unit that is configured to estimate a rough rotational position of the motor based on a combination of a sign of an axis inductive voltage value (e α) of a first coordinate axis and a sign of an axis inductive voltage value of a second coordinate axis (e β) on a two-phase fixed coordinate system, and a magnitude relation between the axis inductive voltage value of the first coordinate axis and the axis inductive voltage value of the second coordinate axis, wherein the rough rotational position estimation unit is configured to estimate in which of eight regions, obtained by dividing the plane of coordinates into eight regions at intervals of 45° in electric angle, the motor rotation angle is located; and a rotation direction estimation unit that is configured to estimate a rotation direction of the motor based on a change in the rough rotational position, estimated by the rough rotational position estimation unit, wherein the estimated motor rotation angle calculation unit is configured to determine a sign of the change amount ( Δθm) based on the rotation direction of the motor, estimated by the rotation direction estimation unit, wherein the estimated motor rotation angle calculation unit is configured to accumulate change amounts ( Δθm) of the motor rotation angle in each calculation period to calculate an estimated motor rotation angle ( θm) by adding or subtracting, based on the determined sign of the change amount, the change amount to a value of the motor rotation angle in an immediately preceding calculation period.