An intake manifold is provided to an internal combustion engine including a first and second cylinder heads each having an intake port. The first and second cylinder heads are distant from each other, and defining a crank angle therebetween. The intake manifold includes a manifold body that defines intake passages each connecting with each intake port. Each intake passage has an interior divided into divisional passages. A butterfly valve communicates and blocks at least one of the divisional passages. Tanks are formed integrally with the manifold body for accumulating negative pressure in the manifold body. The tanks include a first tank, which is provided to the first cylinder head, and a second tank, which is provided to the second cylinder head. An actuator operates the butterfly valve by being applied with negative pressure from the plurality of tanks. The manifold body has a communication passage that communicates the first tank with the second tank.