To improve machinability in a support part of a support shaft for an upper road wheel in a crawler type travelling device.

In the crawler type travelling device 3 supporting the support shaft 53 for the upper road wheel 31 rolling inside of an upper part of a crawler belt 32 for guide so as to be projected from the machine body frame 2 connected to a truck frame 21, the support shaft 53 for the upper road wheel 3 is supported by inserting it into a boss 52 integrally fixed along the machine body frame 2, and the base end side peripheral surface of the support shaft 53 projected from the boss 52 is formed with a double-face width part 53a, and a square washer 55 having an oblong hole 55a is fitted on the double-face width part 53a and fixed by a fixing means, and a peripheral side of the square washer 55 is made to abut on the machine body frame 2 to stop rotation of the support shaft 53.