Subway line 5 has a stop at the airport. There's also a train station. More information about rail connections can be found on the websites of Seoul Metropolitan Subway Corporation and Seoul Metropolitan Rapid Transit Corporation.
Car and bus
Gimpo Airport is situated at short distance from Seoul's center, in the western suburbs of the city. The airport is easily accessible by rental car via the ring road around the center (road number 100). The exit to the airport is clearly signposted.
Because the airport practically lies in the city, many city buses stop at the airport. Apart from buses to the city center, there are also buses to Seoul's larger airport, Incheon Airport. More information about public transport can be obtained via telephone number +82(0)2 2660 2305.
Car rental Airport
You can find a counter of car rental companies in the domestic terminal. Four rental companies are present at Seoul Gimpo Airport, two international ones and two local providers: Avis, Hertz, Jeju and Sambo.
Taxis can be found outside the Arrivals Hall. There are normal and luxury taxis. For the normal taxis the starting rate is 1,900 won and you pay 100 won per 144 meters. The luxury taxis start at a rate of 4,500 won and you add to that 200 won per 164 meters.
There's a large parking lot just outside the terminal. For the first five hours you pay 500 won per 30 minutes, and after that 500 won per 15 minutes. A full day costs 10,000 won. Note: if you park more than a day, the rate of 500 won per 15 minutes applies again!