An unmanned aerial vehicle comprising: a main body ; a plurality of rotary wings provided on the main body; a wire for suspending an object from the main body; a hook attached to the wire ; a sensor for detecting the tension of the wire ; a winch for rotatably supporting a spool on which the wire is wound in the forward and backward directions, winding the wire by rotating the spool in the forward direction and unwinding the wire by rotating the spool in the backward direction; a motor for rotating the spool ; storage for storing a first threshold value S1 for restricting the backward rotation of the spool and a second threshold value S2 for restricting the forward rotation of the spool; and a controller configured to control the motor and restrict the backward rotation of the spool when the tension of the wire becomes less than the first threshold value S1; characterized in that the controller is further configured to (i) determine whether a cargo (M) has been released from the hook and then drive the motor in the forward direction when determining that the cargo (M) has been released from the hook , and (ii) when winding the wire after release of the cargo (M), restrict the forward rotation of the spool when the tension of the wire becomes less than the first threshold value S1 and becomes equal to or less than the second threshold value S2, which is less than a gravitational force acting on the hook ; wherein the inequality of S2 < m1 < S1 < (m1 + m2) is used to determine the first threshold value S1 and the second threshold value S2 where m1 is defined as the gravitational force acting on the hook and m2 is defined as the gravitational force acting on the cargo (M). a main body ; a plurality of rotary wings provided on the main body; a wire for suspending an object from the main body; a hook attached to the wire ; a sensor for detecting the tension of the wire ; a winch for rotatably supporting a spool on which the wire is wound in the forward and backward directions, winding the wire by rotating the spool in the forward direction and unwinding the wire by rotating the spool in the backward direction; a motor for rotating the spool ; storage for storing a first threshold value S1 for restricting the backward rotation of the spool and a second threshold value S2 for restricting the forward rotation of the spool; and a controller configured to control the motor and restrict the backward rotation of the spool when the tension of the wire becomes less than the first threshold value S1; characterized in that the controller is further configured to (i) determine whether a cargo (M) has been released from the hook and then drive the motor in the forward direction when determining that the cargo (M) has been released from the hook , and (ii) when winding the wire after release of the cargo (M), restrict the forward rotation of the spool when the tension of the wire becomes less than the first threshold value S1 and becomes equal to or less than the second threshold value S2, which is less than a gravitational force acting on the hook ; wherein the inequality of S2 < m1 < S1 < (m1 + m2) is used to determine the first threshold value S1 and the second threshold value S2 where m1 is defined as the gravitational force acting on the hook and m2 is defined as the gravitational force acting on the cargo (M). <EOS>