To provide an intake system with a crank room ventilating function for an internal combustion engine, allowing the economical construction of a passage component part in the intake system for introducing crank room gas surely equally distributed into each of cylinders of the internal combustion engine.

The intake system of the internal combustion engine has a ventilating function wherein the crank room gas is introduced into a chamber 18 in the intake system 10. Ventilation is carried out via a passage component part 25 for ensuring introduction to each of intake passages 20a through a plurality of introduction openings 27 in an approximately cylinder selective manner. The passage component part is formed of the inner wall of an intake pipe and closed by a cover 14, therefore permitting inexpensive manufacture of the intake pipe. Advantageously, the result of equal distribution of the crank room gas to the cylinders is obtained and economic manufacture is accomplished.