Two of the six Tunisian international airports are near Kairouan, namely:
Tunis-Carthage International Airport: 150 Km
Monastir International Airport : 60 km
The roads linking Tunis-Kairouan and Monastir-Kairouan are asphalted and in very good condition 100 km of which (Tunis-Enfida) is a toll highway (2.1 Dinars, i.e. 1.5 Euro).

If you are in Tunis and would like to travel to Kairouan, you can take the bus at the Bab-Aliwa Station (there one bus to Kairouan every hour; fare: 8.5 Dinars; 2hs20mns); or take a (more rapid) ‘louage’ (interurban) taxi (carrying 7 passengers and identifiable through their white color with a red stripe) from the Moncef Bey Station (any time; fare: 8.5 Dinars; 1hr45mn).
If you are in Sousse or Monastir, you can do the same for 5 or 6 Dinars.

Distances between Kairouan and important touristic sites in Tunisia.