A work machine comprising: a lower base; a slewing body slewably located on an upper part of the lower base and coupled with a boom that supports a rope that suspends a hoist load; a slewing motor that drives the slewing body; an obstacle detection device located in the slewing body and detecting an obstacle existing in a designated area set within a unique monitoring range; a drive manipulation unit that receives a drive manipulation instructing the slewing motor to operate; and a controller that controls an operation of the slewing motor in response to the drive manipulation, characterized in that the controller includes: a first slewing control unit that sets a first monitoring area that is set with respect to the slewing body as the designated area when the slewing motor is at a stop, and then controls, depending on whether the obstacle is detected in the first monitoring area, whether to prohibit or allow start of the slewing motor in response to the drive manipulation; and a second slewing control unit that sets one or more second monitoring areas that are set at places remoter from the slewing body than the first monitoring area as the designated area, and then controls, depending on whether the obstacle is detected in the one or more second monitoring areas, whether to limit the operation of the slewing motor in response to the drive manipulation after the start of the slewing motor is allowed. a lower base; a slewing body slewably located on an upper part of the lower base and coupled with a boom that supports a rope that suspends a hoist load; a slewing motor that drives the slewing body; an obstacle detection device located in the slewing body and detecting an obstacle existing in a designated area set within a unique monitoring range; a drive manipulation unit that receives a drive manipulation instructing the slewing motor to operate; and a controller that controls an operation of the slewing motor in response to the drive manipulation, characterized in that the controller includes: a first slewing control unit that sets a first monitoring area that is set with respect to the slewing body as the designated area when the slewing motor is at a stop, and then controls, depending on whether the obstacle is detected in the first monitoring area, whether to prohibit or allow start of the slewing motor in response to the drive manipulation; and a second slewing control unit that sets one or more second monitoring areas that are set at places remoter from the slewing body than the first monitoring area as the designated area, and then controls, depending on whether the obstacle is detected in the one or more second monitoring areas, whether to limit the operation of the slewing motor in response to the drive manipulation after the start of the slewing motor is allowed. a first slewing control unit that sets a first monitoring area that is set with respect to the slewing body as the designated area when the slewing motor is at a stop, and then controls, depending on whether the obstacle is detected in the first monitoring area, whether to prohibit or allow start of the slewing motor in response to the drive manipulation; and a second slewing control unit that sets one or more second monitoring areas that are set at places remoter from the slewing body than the first monitoring area as the designated area, and then controls, depending on whether the obstacle is detected in the one or more second monitoring areas, whether to limit the operation of the slewing motor in response to the drive manipulation after the start of the slewing motor is allowed.