The present invention relates to a pilot tone generating method and apparatus of an orthogonal frequency division multiple access system and method, and a channel estimation method and apparatus using the same. The channel estimation apparatus includes a pilot tone extracting unit for extracting a pilot tone, which is inserted within a frame with data tone, masked with an orthogonal code; a pilot tone unmasking unit for unmasking of the pilot tone extracted from the pilot tone extracting unit by using an orthogonal code information; and a channel estimation operating unit for estimating a channel by calculating an average of the pilot tones which is unmasked in the unmasking unit.