To provide the travelling device of a large-sized conveying vehicle in which a steering angle of a tire is increased with a simple structure.

The travelling device 12 of the large-sized conveying vehicle includes a travelling mechanism having a tire 21 rotatable via a travelling motor 26 or an axle 25, a lifting mechanism that moves the travelling mechanism up and down relative to a vehicle body by using an actuator 24, and a steering mechanism that rotates a rotary bracket 22 rotatably supporting the travelling mechanism and the lifting mechanism. The steering mechanism includes a bearing 31 fixed to the rotary bracket 22 on the side close to an outer wheel 311 and fixed to a vehicle body side on the side close to an inner wheel 312 for transmitting rotation of a steering motor via a worm gear 32 to the outer wheel 311 of the bearing 31.