A bottom surface of a surge tank has such a shape that, in a vehicle-mounted state, the bottom surface is positioned below a lower surface at an upstream end of each of a plurality of independent passages and comes closer to the lower surface at the upstream end of each of the plurality of independent passages in a vertical direction farther away from a connected portion between the surge tank and a third passage in a cylinder array direction.

A bottom surface of a surge tank has such a shape that, in a vehicle-mounted state, the bottom surface is positioned below a lower surface at an upstream end of each of a plurality of independent passages and comes closer to the lower surface at the upstream end of each of the plurality of independent passages in a vertical direction farther away from a connected portion between the surge tank and a third passage in a cylinder array direction.

Intake ports include a second port configured such that a flow rate of flowing gas is adjusted via a swirl control valve. When a surge tank is viewed in a cylinder axis direction, first and second branched passages are connected with a space being interposed therebetween in a cylinder array direction, and are connected to the surge tank on extension lines, each of which extends from an upstream end portion of an independent passage connected to the second port to an opposite side of each cylinder.