< Topic >The nail coating flux which can control the fact that color of the area nail due to sticking the nail seal becomes turbid white is offered. SolutionsBeing the method of forming coating membrane 15 in nail 52, it includes with the process which applies the nail coating flux 10 which from the melting liquid which makes the shellac and the particular shellac melt is formed, to the surface of nail 52 and the process which makes nail coating flux dry 10, it is formation method of coating membrane 15. < Selective figure >Figure 1【課題】ネイルシールの貼付による地爪の色が白く濁ることを抑制できる爪被覆剤を提供する。【解決手段】爪52に被覆膜15を形成する方法であって、シェラックと当該シェラックを溶解させる溶解液とから構成された爪被覆剤10を、爪52の表面に塗布する工程と、爪被覆剤10を乾燥させる工程とを含む、被覆膜15の形成方法である。【選択図】図1