To provide a motor controller preventing sudden stop of a motor in the case of overheating while waste of energy is suppressed, and to provide a control method.

A point value corresponding to a load state of the motor is set. The load state of the motor is detected and a motor load point PointF of a wiper motor is calculated (S1). The motor load point PointF is compared with thresholds A to C (S3 to S5). Overheat protection processing such as an energy wiping mode (S6) in which number of revolutions of the motor is reduced gradually, an intermittent wiping operation (S7) and a motor stop (S8) is performed based on respective comparison results. The overheat protection processing is canceled when the motor load point PointF becomes a release threshold X or below and a wiper switch is turned off (S10 to S12).

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