A frameless type working vehicle includes an intermediate vehicle body 5 acting as a body forming member for interconnecting a front vehicle body 3 and a rear vehicle body 4. The intermediate vehicle body is formed of a case block 10 housing a hydrostatic stepless transmission (HST) 20. The case block 10 includes, formed integral with one another, a small diameter portion 11 connected to the rear vehicle body 4 and providing case walls for a pump P and a motor M of HST 20, a large diameter portion 12 connected to the front vehicle body 3 and having an upper edge at a higher level than an upper surface of the small diameter portion 11, and a transitional portion 12A disposed between the small diameter portion 11 and the large diameter portion 12. The large diameter portion 12 defines an accommodating space S1 for a main clutch 9 that receives drive from an engine E.