When a slewing motor is at a stop, a first slewing control unit of a controller that controls an operation of the slewing motor sets a first monitoring area that is set with respect to a slewing body as a designated area, and then controls, depending on whether an obstacle is detected in the first monitoring area, whether to prohibit or allow start of the slewing motor in response to a drive manipulation. Furthermore, a second slewing control unit of the controller 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 second monitoring area(s), whether to limit the operation of the slewing motor in response to the drive manipulation after the start of the slewing motor is allowed.

When a slewing motor is at a stop, a first slewing control unit of a controller that controls an operation of the slewing motor sets a first monitoring area that is set with respect to a slewing body as a designated area, and then controls, depending on whether an obstacle is detected in the first monitoring area, whether to prohibit or allow start of the slewing motor in response to a drive manipulation. Furthermore, a second slewing control unit of the controller 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 second monitoring area(s), whether to limit the operation of the slewing motor in response to the drive manipulation after the start of the slewing motor is allowed.

Provided is a parking brake apparatus installable on a work machine. The parking brake apparatus includes: a parking brake switchable between a braking state of braking the turning of an upper turning body and a braking release state; a brake operation device to which a braking operation and a braking release operation for switching the parking brake to the braking state and the braking release state, respectively, is applied by an operator; and a braking control unit. The braking control unit judges whether or not a turning judgment requirement for judging whether or not the upper turning body is performing a turning motion is satisfied, and performs a braking operation invalidation control to invalidate the braking operation applied to the brake operation device when judging the turning motion is being performed.

Provided is a parking brake apparatus installable on a work machine. The parking brake apparatus includes: a parking brake switchable between a braking state of braking the turning of an upper turning body and a braking release state; a brake operation device to which a braking operation and a braking release operation for switching the parking brake to the braking state and the braking release state, respectively, is applied by an operator; and a braking control unit. The braking control unit judges whether or not a turning judgment requirement for judging whether or not the upper turning body is performing a turning motion is satisfied, and performs a braking operation invalidation control to invalidate the braking operation applied to the brake operation device when judging the turning motion is being performed.