Inchoeon(ICN) International Airport

There are two luggage storages on 3rd floor(departure floor).

One at next to island B, the other is at next to island M.

Open hour : 06:00 ~ 22:00
Price : I'm not sure, but I don't think it is too expensive.

More infomation Here

 

Gimpo International Airport

The 2th floor:

Luggage Storage (032-743 5804; Gate B; per item per day W3000-6000; 6am-10pm)

Read more: http://www.lonelyplanet.com/south-korea/seoul/transport/getting-there-around#ixzz32dUHYOaD
 

Ther 3th floor:

Left-Luggage Storeroom (large item per day W3000; 7am-9.30pm)
Read more: http://www.lonelyplanet.com/south-korea/seoul/transport/getting-there-around#ixzz32dUU0FJR
 

 

The 4th floor has restaurants and duty-free shops. Shops, banks, lost luggage, luggage deposit and a medical centre are also available.
Read more: http://www.lonelyplanet.com/south-korea/seoul/transport/getting-there-around#ixzz32dU969jY
 

 

Seoul Station

1) Baggage storage service

 

Take advantage of our check-in services for hand luggage so you can take in the sights around Seoul Station

Hours of operation : 08:00 to 20:00

Rate: Small - 3,000KRW / Medium - 5,000KRW / Large - 7,000KRW / X-Large - 10,000KRW (per Item/Tax Included)※ Please note that items not picked up during business hours will not be available until the following day,    and an additional fee will apply.

We do not store the luggage as below:(1) The luggage weight over 30kg per one bag(2) An explosive or dangerous object(3) Animals(4) Perishable product(5) Works of art, antiques, crafts, jewelry, and other valuables

More information:Here

 

CERESTAR

1,000KRW ,1,200KRW,1,500KRW

You can leave your luggage 24 hours

When the storage period has passed three days, it is stored in a different location