An intake manifold includes a passage wall portion having a first member passage wall portion provided at a first member, a second member passage wall portion provided at a second member, and an inner joint portion including a division point at which an inner joint portion is divided from an outer peripheral joint portion, the inner joint portion at which the first member passage wall portion and the second member passage wall portion are joined with each other. At least a part of the inner joint portion except for the division point is arranged at a height position closer to a middle part of a gas passage than the division point in a first direction in which the first member and the second member are opposed with each other.