To provide a ventilation system or the like, capable of easily matching, even in a combination of cooking equipment and a ventilation device differed in signal identification code, the identification codes with each other and used immediately after installation.

In the ventilation system 1, an identification code A0 of signal transmitted from a transmission part 10 of a cooker 2 is differed from an identification code Ax of signal receivable by a receiving part 15 of the ventilation device 3. A microphone 8 detects a sound generated in rotation of a ventilation fan 11 of the ventilation device 3, and transmits the detection signal to a signal converter 5. The identification code Ax receivable by the receiving part 15 is automatically selected and determined from candidate identification codes An (n=1, 2, 3, etc.) by effects of the signal converter 5 and the microphone 8. Thereafter, the signal converter 5 entirely converts the received identification code A0 of signal to the determined identification code Ax.