To provide an amphibious working vehicle that can completely float on the water surface, and can move even while being completely floated on the water surface, and thereby can be used for the offshore work away from a seashore and a lakefront.

An amphibious working vehicle includes: a working vehicle body equipped with a mechanism for performing water work; a crawler part with a caterpillar for making the working vehicle body travel; and a float part for providing buoyancy to the working vehicle body. The float part comprises: a main float disposed in the caterpillar of the crawler part; and a sub-float mounted to the lateral side of the main float. On an outer circumferential surface of the caterpillar, fins are provided for generating propulsive force on the water surface by paddling accompanying the rotation of the caterpillar.