To compactify a transmission case and a transmission structure and to reduce the manufacturing cost.

A variable-speed pump 67, a variable-speed motor 68, a steering pump 69, and a steering motor 70 of a hydraulic continually variable transmission structure are fitted to a transmission case 23 in this crawler travel vehicle. The same transmission shaft 96 in the transmission case 23 is used in common as a fixed shaft provided with a turn transmission mechanism 108, a transmission drive shaft transmitting the travel transmission driving force, and parking brake shafts braking travel crawlers 2.