A rear limiting mechanism (35) for limiting a moving range in a vertical direction, a front-rear direction and a lateral direction of the cab frame (24) is arranged immediately below a rear pillar (30) of the cab frame, between the vehicle body frame (21) and both right and left end portions of the higher portion of the cab frame (24). The rear limiting mechanism (35) includes a limitation member (36), limiting members (37, 38) and a limiting pin (40). Gaps (S1a, S1b) are provided between the limiting pin (40) and the limitation member (36), gaps (S2a, S2b) are provided between the limitation member (36), and the front limiting member (37) and the rear limiting member (38). Gaps (S3a, S3b) are provided between the limiting pin (40) and the limitation member (36). A movement of the cab frame (24) is limited within the ranges of the gaps. A check plate (41) is fixed to the limiting pin (40), and a bolt (42) extending through the check plate (41) is engaged with a threaded hole (38b) of the rear limiting member (38). The rear limiting mechanism (35) supports a rear portion of the cab frame, at a time when a crawler dozer rolls over or the like. The rear limiting mechanism (35) having the simple structure is provided at only two positions corresponding to the rear pillars (30).