A pitch control device for a windmill that includes a battery capable of applying electricity to a motor of a pitch drive device for changing a pitch angle of a blade of a windmill that is rotatably provided on a main shaft portion of the windmill, and that controls the pitch angle of the blade with the electricity of the battery such that the pitch angle is changed in a direction in which the wind pressure exerted on the blade is reduced, the pitch control device comprising: a motor controller that controls storage and discharge of electricity into and from the battery and controls the motor based on a control signal from a pitch controller that outputs the control signal for changing the pitch angle of the blade; an induction motor provided as the motor; a switching box capable of switchably connecting an external power source supplied as an alternating-current power source and the battery to the induction motor; a first abnormality detector that detects an abnormality of the external power source; and a second abnormality detector (19, 24-29) that detects an abnormality of the motor controller; wherein, during a normal operation, the motor controller controls the induction motor based on a control signal from the pitch controller, wherein, when the first abnormality detector detects an abnormality of the external power source, the switching box connects the induction motor to the battery, and controls the pitch angle of the blade such that the pitch angle is changed in a direction in which wind pressure is reduced, and, when the second abnormality detector (19, 24-29) detects an abnormality of the motor controller, the switching box directly connects the induction motor to the external power source without the motor controller intervening, and controls the pitch angle of the blade such that the pitch angle is changed in a direction in which wind pressure is reduced. a motor controller that controls storage and discharge of electricity into and from the battery and controls the motor based on a control signal from a pitch controller that outputs the control signal for changing the pitch angle of the blade; an induction motor provided as the motor; a switching box capable of switchably connecting an external power source supplied as an alternating-current power source and the battery to the induction motor; a first abnormality detector that detects an abnormality of the external power source; and a second abnormality detector (19, 24-29) that detects an abnormality of the motor controller; wherein, during a normal operation, the motor controller controls the induction motor based on a control signal from the pitch controller, wherein, when the first abnormality detector detects an abnormality of the external power source, the switching box connects the induction motor to the battery, and controls the pitch angle of the blade such that the pitch angle is changed in a direction in which wind pressure is reduced, and, when the second abnormality detector (19, 24-29) detects an abnormality of the motor controller, the switching box directly connects the induction motor to the external power source without the motor controller intervening, and controls the pitch angle of the blade such that the pitch angle is changed in a direction in which wind pressure is reduced.