The hydraulic steering mechanism according to the present invention includes an axle case, a first steering case, a second steering case, a first arm, a second arms, a third arm, a hydraulic actuator, and a tie rod. The first, second and third arms are provided to the first steering case, the second steering case and the axle case, respectively. The hydraulic actuator includes a cylinder and a piston for moving with respect to each other by an action of hydraulic pressure. The first and second arms have tie rod mounting portions to which the tie rod is mounted. At least one of the first and second arms has a first hydraulic actuator mounting portion to which one of the cylinder and the piston in the hydraulic actuator is mounted. The third arm has a second hydraulic actuator mounting portion to which the other of the cylinder and the piston in the hydraulic actuator is mounted. The first hydraulic actuator mounting portion is at a longer distance from axis lines of the differential yoke shafts than the second hydraulic actuator mounting portion in a plan view when the vehicle is traveling substantially straight.