Provided is a slewing type construction machine including an upper slewing body and a slewing speed sensor that detects a slewing speed of the upper slewing body, the construction machine enabling accurate control to be achieved regardless of an error in output from the slewing speed sensor. The construction machine includes an upper slewing body, a slewing motor (8), a hydraulic pump (7), a control valve (10), a slewing operation device (11), a slewing brake (12), a slewing speed sensor (27), a slewing operation detector (26) that detects an operation applied to the slewing operation device to output a slewing operation signal, and a controller (17). The controller (17) stores, during a slewing operation, a slewing speed detected by the slewing speed sensor (27) at set time intervals, actuates the slewing brake (12) based on a neutral return operation of the slewing operation device (11), and resets a stored value of the slewing speed that is stored during actuation of the slewing brake, to zero.