To reduce weight of a cab tilt device by preventing lowering of a cab even when a mechanical cab lowering preventive device is eliminated.

A stay 11 is supported free to slide by a slide guide 10 on a cylinder 5 of a cylinder device 4 interposed between a cab 1 and a frame 2 and to tilt the cab, and an upper end part of the stay 11 is connected to a head end part of a piston rod 6 of the cylinder device. A stop switch 25 to maintain stopping of an electric motor of the cylinder device 4 is arranged on an upper end part of the cylinder 5, a stop lever 17 to actuate the stop switch 25 by revolving at the time when a sliding end part 18 is positioned at a first inclined surface part 13 of the stay 11 is supported on the upper end part of the cylinder 5, and a release lever 21 is linked to the stop lever 17. Consequently, it is possible to prevent lowering of the cab, accordingly, to eliminate a mechanical cab lowering preventive device and to reduce weight and cost of a cab tilt device.