An air conditioner in which an indoor device and an outdoor device are separately provided, the air conditioner comprising: an outdoor fan that is provided in the outdoor device; a permanent magnet synchronous motor that drives the outdoor fan, wherein the motor is rotated by natural force; an inverter of which power is supplied from a direct-current power supply and which applies a voltage to the permanent magnet synchronous motor; an inverter control unit that controls a voltage output from the inverter; a current detection unit that is connected between the direct-current power supply and the inverter; and a protection circuit that detects a current flowing through the current detection unit and executes a protection of the inverter, wherein the inverter control unit is configured to include a brake sequence that brakes the natural rotation of the outdoor fan, the brake sequence is configured to execute a control of performing a line-to-line open circuit or a line-to-line short-circuit of the permanent magnet synchronous motor based on information on a conduction ratio, wherein the information on the conduction ratio is set such that a time period of short circuit becomes longer along with a time lapse of brake control and is set so as to be in a range from a starting-time conduction ratio which is a conduction ratio at a time of starting braking to an ending-time conduction ratio which is a conduction ratio at a time of ending braking, the brake sequence is configured to set the starting-time conduction ratio such that the protection circuit is able to detect the current flowing through the current detection unit when a semiconductor switching element of the inverter has a short-circuit fault, characterized in that the brake sequence is further configured to set the starting-time conduction ratio according to capability of the protection circuit such that a time of short circuit is longer than the necessary time of the protection circuit to detect the current flowing through the current detection unit and execute protection of the inverter by causing the inverter control unit in response to receiving a protection signal from the protection circuit to perform control of the inverter so that the inverter does not output any voltage to the permanent magnet synchronous motor. an outdoor fan that is provided in the outdoor device; a permanent magnet synchronous motor that drives the outdoor fan, wherein the motor is rotated by natural force; an inverter of which power is supplied from a direct-current power supply and which applies a voltage to the permanent magnet synchronous motor; an inverter control unit that controls a voltage output from the inverter; a current detection unit that is connected between the direct-current power supply and the inverter; and a protection circuit that detects a current flowing through the current detection unit and executes a protection of the inverter, wherein the inverter control unit is configured to include a brake sequence that brakes the natural rotation of the outdoor fan, the brake sequence is configured to execute a control of performing a line-to-line open circuit or a line-to-line short-circuit of the permanent magnet synchronous motor based on information on a conduction ratio, wherein the information on the conduction ratio is set such that a time period of short circuit becomes longer along with a time lapse of brake control and is set so as to be in a range from a starting-time conduction ratio which is a conduction ratio at a time of starting braking to an ending-time conduction ratio which is a conduction ratio at a time of ending braking, the brake sequence is configured to set the starting-time conduction ratio such that the protection circuit is able to detect the current flowing through the current detection unit when a semiconductor switching element of the inverter has a short-circuit fault, characterized in that the brake sequence is further configured to set the starting-time conduction ratio according to capability of the protection circuit such that a time of short circuit is longer than the necessary time of the protection circuit to detect the current flowing through the current detection unit and execute protection of the inverter by causing the inverter control unit in response to receiving a protection signal from the protection circuit to perform control of the inverter so that the inverter does not output any voltage to the permanent magnet synchronous motor.