An air intake device 40 comprises: a surge tank 44 having an upper tank chamber 50, a lower tank chamber 52, and a communication portion 56; a first intake pipe 46 having communication with the upper tank chamber 50; a second intake pipe 48 having communication with the lower tank chamber 52; and a valve 58 disposed in the lower tank chamber 52, the valve 58 being displaced between a closed position, in which an internal space of the lower tank chamber 52 is divided into a main space 60 having communication with the second intake pipe 48 and a sub-space 62 facing the communication portion 56, and an open position, in which the main space 60 and the sub-space 62 are integrated with each other.