PURPOSE: To provide an exhaust device simple in structure and low-priced, enabling the improvement of exhaust brake effect while securing the durability of valve members such as an exhaust valve, a cooperating valve seat and an exhaust cam in a vehicular engine provided with an exhaust braking device.

CONSTITUTION: A cylinder head is provided with a cylindrical recessed part 26 formed in the state of surrounding the valve stem guide of an exhaust valve 20. A lower retainer 28 operated as a movable piston is fittingly inserted in the cylindrical recessed part 26, and a valve spring 36 is provided in the contracted state between the lower retainer 28 and an upper retainer 32 mounted to the vicinity of the tip of an exhaust valve stem. An exhaust braking device 40 is interposed in an exhaust system, and a communicating passage 38 for communicating an exhaust port 12 with the bottom part of the cylindrical recessed part 26 is provided in the cylinder head. At the operating time of the exhaust braking device 40, exhaust gas pressure in the exhaust system is led into the cylindrical recessed part 26 from the communicating passage 38, and the lower retainer 28 is displaced to compress the valve spring 36, thus increasing the valve opening force of the exhaust valve 20 temporarily.