The sem package in R was introduced in latent growth modeling analysis. The sample date in this analysis were selected from the published official batting average records of professional Japanese baseball players over a period of ten years. The result of latent growth modeling demonstrated that the quadratic form trajectory model fit the data well. The R command lists of this analysis were also presented. Rのsemパッケージを，潜在成長モデルの分析のために紹介した.この分析の例データのために，10年にわたる日本のプロ野球選手の打撃記録を刊行されている公認記録から選んだ.潜在成長モデルの結果は,二次形式の軌跡モデルがよくデータに合うことを明らかにした.この分析のRコマンドリストも提示した
