PURPOSE: To excellently secure the front visibility from an operation part by arranging a hood to house an engine in a front part of a machine body frame, interlocking/connecting a work machine with/to a rear part of the machine body frame, and arranging a muffler continuously arranged on the engine in the hood.

CONSTITUTION: In the agricultural tractor, an engine E is housed in a hood arranged in a machine body frame front part, and is formed as a prime mover part, and a rotary cultivating work machine is connected to a rear end part of a machine body frame 1 through a three-point link mechanism and a raising- lowering mechanism so as to be freely raised and lowered. A muffler M continuously arranged on the engine E is arranged in the hood B. In this case, the muffler M is arranged in a left side upper part of the engine E so that its lengthwise direction turns in the same direction with the advancing direction of a machine body, and a base end part is connected to a turbocharger T through an exhaust pipe 31. The tip of the exhaust pipe 31 is extended to the side from a tip part, and its tip is projected outward from a left side surface B1 of the hood.