To operate a work by oblique motion even under the condition of requiring severe stopping accuracy and handle operating accuracy by providing a rotational center position changeover means for changing the position of rotational center independent of the advancing direction so as to easily correct dislocation.

An operator operates a carrier car so that a beam projected to a running guide line during running is on the running guide line. When dislocation is generated, namely, under the condition of setting the advancing direction right, by setting a front/rear changeover lever to be front drive, the carrier car front part 10f precedes. By setting it to be rear drive, the carrier car rear part 10r precedes, and hence the moving direction set by the front/rear right/left advancing lever and the moving direction of a driver's cab 14 can be conformed to each other. Even under the condition of setting the advancing direction left, by the front/rear drive changeover lever, the moving direction set by the front/ rear right/left advancing lever and the moving direction of the driver's cab 14 can be similarly conformed to each other.