PURPOSE: An accompaniment providing method and an accompaniment providing system using the same are provided to provide an accompaniment which fits for the intonation and rhythm of a user by extracting a melody from a sound and searching the most similar sound source. CONSTITUTION: A sound signal is inputted from an external input unit to a signal input unit (105). Information about multiple sound sources is stored in a sound source database. A melody extracting unit (110) divides a melody into preset time interval frames. The melody extracting unit extracts a melody about each frame. A chromatic scale converting unit (120) converts the melody about each frame which is extracted by the melody extracting unit into a chromatic scale. An onset detecting unit detects and provides onset information about each frame. [Reference numerals] (100) Sound source database; (105) Signal input unit; (110) Melody extracting unit; (120) Chromatic scale converting unit; (130) Onset extracting unit; (140) Melody sequence estimating unit; (150) Similar sound source selecting unit; (160) Accompaniment correction unit; (170) Accompaniment output unit