To keep the center of gravity of a machine body at a low position, and secure the stability of a working posture regardless of movement of the center of gravity following the rotation of a rotary base at the time of work in a wheel type work machine.

An actuator 111 that actuates integrally with an axle case 96 is disposed at a width center of the axle case 96. A swinging lock mechanism 112 is disposed to regulate swinging of the actuator 111. The swinging lock mechanism 112 is provided with a lock cylinder 115 in which a piston rod 120 is horizontally fixed to a machine frame 6, and a changeover valve 118 to switch second oil chambers 124A and 124B of the lock cylinder 115 to a continuity state or a closed state. A cylinder tube 116 of the lock cylinder 115 is interlocked and connected to the actuator 111.