An intake system of an engine is provided, which includes a first passage provided to an engine bay, for leading fresh air to the engine, a second passage branched from the first passage and extending toward a cabin, and an intake noise increasing device provided to the second passage. The intake noise increasing device has a cylindrical bellows part, a vibrating membrane formed integrally with the bellows part to close a first opening of the bellows part, and an outer circumferential case provided to cover an outer circumference of the bellows part and configured to allow the expansion and contraction of the bellows part therein. The second passage has a deriving passage section connected to a part of the outer circumferential case on a first opening side and extending toward the cabin. The deriving passage section is disposed to be lowered while separating from the intake noise increasing device.