To securely perform emission control from a cold start without impairing a performance in normal operation.
This exhaust emission control device of the internal combustion engine comprises a first exhaust port 4 communicating with a combustion chamber 19 formed on the lower surface of a cylinder head 1, a first exhaust valve 7 opening and closing the first exhaust port 4, a first exhaust pipe 11 connected to the first exhaust port 4 and leading the exhaust gas in the combustion chamber 19 to the atmosphere, and a first catalyst 14 purifying the exhaust gas. The exhaust emission control device also comprises a second exhaust port 5 formed separately from the first exhaust port 4 and communicating with the combustion chamber 19, a second exhaust valve 8 opening and closing the second exhaust port 5, a second exhaust pipe 12 allowing the second exhaust port 5 to communicate with the first catalyst 14 or the upstream part of the first exhaust pipe 11 from the first catalyst 14, a second catalyst 13 smaller in size than the first catalyst 14 which is installed in the second exhaust pipe 12, a catalyst activation determination means 20 determining the active state of the first catalyst 14, and an exhaust valve control means 20 controlling the operations of the first exhaust valve 7 and the second exhaust valve 8 according to the determined results of the catalyst activation determination means 20.
Yoshio Matsuda