An internal combustion engine comprising: a camshaft having a first exhaust cam and a second exhaust cam on an outer circumferential surface thereof, said camshaft being rotatable in ganged relation to rotation of a crankshaft; a first exhaust valve opening and closing a first exhaust port which faces a combustion chamber; a second exhaust valve opening and closing a second exhaust port which faces the combustion chamber; a first rocker arm actuating said first exhaust valve to open and close by being pushed by said first exhaust cam; a second rocker arm actuating said second exhaust valve to open and close by being pushed by said second exhaust cam; and a decompression mechanism rotatable in unison with said first exhaust cam projecting a decompression operator to lift said first rocker arm in a valve opening direction at a timing of a compression stroke initiated by the internal combustion engine when a rotational speed of said camshaft is lower than a predetermined rotational speed, and retracting said decompression operator when the rotational speed of said camshaft is equal to or higher than the predetermined rotational speed, characterized in that said first rocker arm and said second rocker arm are provided with an angular movement transmitter transmitting a turning force produced by said decompression operator in the valve opening direction from said first rocker arm to said second rocker arm; and said angular movement transmitter includes a pair of protrusions (22A-b, 22B-b) projecting toward each other from respective rocker arm bodies (22A-a, 22B-a) of said first rocker arm and said second rocker arm and abutting against each other when said first rocker arm is turned in the valve opening direction by said decompression operator. a camshaft having a first exhaust cam and a second exhaust cam on an outer circumferential surface thereof, said camshaft being rotatable in ganged relation to rotation of a crankshaft; a first exhaust valve opening and closing a first exhaust port which faces a combustion chamber; a second exhaust valve opening and closing a second exhaust port which faces the combustion chamber; a first rocker arm actuating said first exhaust valve to open and close by being pushed by said first exhaust cam; a second rocker arm actuating said second exhaust valve to open and close by being pushed by said second exhaust cam; and a decompression mechanism rotatable in unison with said first exhaust cam projecting a decompression operator to lift said first rocker arm in a valve opening direction at a timing of a compression stroke initiated by the internal combustion engine when a rotational speed of said camshaft is lower than a predetermined rotational speed, and retracting said decompression operator when the rotational speed of said camshaft is equal to or higher than the predetermined rotational speed, characterized in that said first rocker arm and said second rocker arm are provided with an angular movement transmitter transmitting a turning force produced by said decompression operator in the valve opening direction from said first rocker arm to said second rocker arm; and said angular movement transmitter includes a pair of protrusions (22A-b, 22B-b) projecting toward each other from respective rocker arm bodies (22A-a, 22B-a) of said first rocker arm and said second rocker arm and abutting against each other when said first rocker arm is turned in the valve opening direction by said decompression operator.