Abstract: A liquid painting instrument according to the present invention includes a main shaft oval-shaped in cross-section, a cap of the same configuration and an elastically deformable O-ring. The O-ring is put on the front end outer periphery of the main shaft such that it may be securely fastened to the inner face of the cap by being elastically deformed following both the configurations of the main shaft and the cap. A front end shaft attached to the main shaft incorporates a plurality of paint cores and comb teeth that are mounted along a major axis of the front end shaft and parallel to each other.