PROBLEM TO BE SOLVED: To provide a simple plaque formation preventive agent that has a high plaque formation prevention effect and in which an effect can be obtained even when added at a level where the bitterness and astringency is not a problem.SOLUTION: Provided is a plaque formation preventive agent containing tea extract catechin. The tea extract catechin preferably is epigallocatechin gallate, and the tea extract catechin in which the specific optical rotation when dissolved in ethanol is -150.0 to -180.0 deg, and, when HPLC analysis using an optical isomer column is performed, the area ratio of the detection peak of (-)-epigallocatechin gallate to the peak of retention time of 4.6 to 5.2 minutes detected immediately before is 1: 0.005 to 0.10, is particularly effective.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2020,JPO&INPIT【課題】歯垢形成予防効果が高く、苦渋味が問題とならない程度で添加しても効果が得られる簡易な歯垢形成予防剤の提供。【解決手段】茶抽出物カテキンを含む歯垢形成予防剤。茶抽出物カテキンはエピガロカテキンガレートであることが好ましく、エタノールで溶解した場合の比旋光度が－１５０．０～－１８０．０ｄｅｇ、光学異性体カラムを用いたＨＰＬＣ分析を行った場合に、（－）－エピガロカテキンガレートの検出ピークと、その直前に検出される保持時間４．６～５．２分のピークの面積比が１：０．００５～０．１０である茶抽出物カテキンが特に効果が高い。【選択図】図１
