By bus
On weekdays, a few HT busses go all the way to the Roskilde Airport terminal building. If you take any other HT bus, you should get off the bus on Køgevej, just opposite Lufthavnsvej. From there, it is a walk of about 1.7 km to the terminal building.
Bus nos. 210, 212 and 213 go either to Roskilde Airport or the road by the airport.
Click here for more information on the bus lines http://www.moviatrafik.dk/