An exhaust manifold that comprises an open/close valve that switches between either closing or opening the exhaust path of a collection section, and switches the exhaust path of the exhaust gas between passing through or not passing through a bypass path containing a upstream (front) catalyst; it can improve flow of exhaust gas when the open/close valve is completely closed, and reducing exhaust interference and loss of exhaust heat. There is a partition wall structure 12 in a pipe-mounting member 11 so that when the open/close valve 15 is closed such that the exhaust gas during cold start is led to the upstream (front) catalyst, the exhaust paths for each of the branch pipes 3 on the upstream side of the open/close valve 15 inside a collection section 4 are made independent from one another. When the open/close valve 15 is closed, the downstream side of each of the branch pipes 3 is not continuous inside the collection section 4, so the flow of air is prevented in this section, and exhaust interference and loss of exhaust heat are reduced.