SWIVEL WORK MACHINE

In order to accurately detect a posture angle of a swivel section even when a disturbance acceleration occurs due to the movement of the swivel section, a swivel work machine includes: a swivel section; at least one inertial sensor (30) that is disposed on the swivel section and that is configured to calculate a posture angle of the swivel section on the basis of an angular velocity and an acceleration; a first operation detection section as a detection section (81) configured to detect an operation of causing the swivel section to move; and an IMU instruction section as an output section (83) configured to, in a case where an operation of causing movement has been detected, output a signal corresponding to the operation, to the at least one inertial sensor.