To provide a crawler vehicle with variable gage mechanism expanding/ contracting width of a track gage from a driver's seat by controlling operation of a link mechanism by a hydraulic cylinder and a variably setting method of the track gage width of this crawler vehicle.

A vehicle comprises a variable gage spreading/contracting switch 24, variable gage operating valve 22, 23 operated by a variable gage operating lever 21 and attached valve operating piece 21a and a pilot pressure solenoid switching valve 26, positioning hydraulic cylinder 15 fixing or unfixing a connection link by either spreading or contracting a gage space between track frames and a fixing pin 17, connection link constituting a parallel 4-node link and its operating hydraulic cylinder 10, and a controller 25 obtaining a signal of an action indicating means to transmit any operational signal either spreading or contracting to a switching valve 28 on a track gage variable hydraulic circuit.