For the last century, various and contradicting opinions and interpretations on the topic, 'galant style' of the eighteenth century have been rampant. The fundamental cause lies in music theory books in the eighteenth century which have not presented consistent definition and evaluation on present musical phenomenon. This article aims at investigating the fundamental causes and examined 'galant style' mentioned in the theoretical books in the eighteenth century. The results show as follows: Aspects of understanding 'galant style' until it is regarded in the same light as 'freier Stil' as it started from the music of galant homme, which is a social ideal rooted in France, but voices on identification of external identity mostly remains silent. This hindered establishment of the concept of 'galant style' as a substantial music style. In order to define 'galant style' properly and identify historical identity objectively, studies on the works of the time which are mostly still unknown have to be preceded.