To reduce the cost, facilitate the on-vehicle layout, and reduce the deterioration of a catalyst in an emission control device for engine for reducing a toxic component of the emission components from an engine by oxidizing reaction or reducing reaction using the catalyst. thereby purifying emission.

This device has only one catalytic converter 3 provided only in the middle of exhaust passages 1, 2, and a control unit 10 controls the opening and closing first, second, third and fourth control valves 6, 7, 8, 9 in such a manner as to form a straight route for carrying emission from the upstream exhaust passage 1 toward the downstream exhaust passage 2 only within the exhaust passages 1, 2 having the catalytic converter 3 provided therein in a general time when the exhaust temperature is not high; and an S-shaped route for carrying the emission to the rear surface side of a catalyst 3a through a first bypass passage 4, at a high exhaust temperature, and carrying after passed through the catalyst 3a, from the front surface side of the catalyst 3a to the muffler side exhaust passage 2 through a second bypass passage 5.