Provided is a construction machine including an electric-component box capable of easy removal for maintenance of a maintenance-requirement device. The construction machine includes a seat stand (10), a partition wall (15) provided in an under-seat space (S2) under the seat stand (10) to define a front space (16), an electric-component box installed in the front space (16), a maintenance-requirement device (23) located rearward of the front space (16), and a harness (29) connecting an electric component (18) in the electric-component box (19) to an external device. The harness (29) includes a downward-extending portion (29b) extending downward from the height of a wiring port (30) in the seat stand (10) and an upward-extending portion (29e) extending upward from the height position of a lower end of the downward-extending portion (29b), thus routed in a devious path including allowance enough to allow removal of the electric-component box (23) between a position for closing a rear opening (22) in the partition wall (15) and a position for allowing maintenance work for the maintenance-requirement device (23) through the rear opening (22).