To provide an intake air amount control device of internal combustion engine capable of maintaining a stable engine combusting conditions by suppressing the occurrence of a spitting phenomenon at low speed and load.

An air intake pipe 11 is connected to an air intake port 9 provided in each cylinder of an engine 1 through an air intake manifold 11a. Also a bypass path 22 for connecting the upstream of a throttle valve 19 to the downstream of it is provided in the air intake pipe 11. An idle control valve 23 for adjusting an intake air amount at idling is installed in the bypass path 22. An air intake control valve 24 is installed in the air intake manifold 11a. In addition, in idling operation, an ECU 51 opens the air intake control valve 24 controllably after a valve overlap time has been passed, and closes it controllably when a specified time has been passed after the air intake valve 13 has been closed.