PROBLEM TO BE SOLVED: To provide stable injection solutions of concentrated sterilized pemetrexed or a pharmaceutically acceptable salt thereof without using any antioxidant.SOLUTION: A stable injection solution of pemetrexed which comprises pemetrexed or a pharmaceutically acceptable salt thereof having dissolved oxygen content ranging from 0 to 0.2 ppm, and water for injection contains no stabilizer or solubilizer and is contained in a container sealed by a stopper, the amount of all impurities in the container not increasing more than 2.0% by weight of pemetrexed when the solution is stored in room temperature for one year. The injection container is made of a hard material, preferably being a glass vial.SELECTED DRAWING: Figure 1【課題】抗酸化剤を使用せずにペメトレキセドの濃縮無菌溶液をペメトレキセドまたはその薬剤的に許容できる塩の安定な注射溶液の提供。【解決手段】溶存酸素含有量が0~0.2ppmの範囲内にある、ペメトレキセド又はその薬剤的に許容できる塩、注射用水を含んでなるペメトレキセドの安定な注射溶液であって、安定剤または可溶化剤を含まず、ストッパーで密閉された容器に入れられ、前記溶液中の全不純物が、室温で1年間貯蔵された場合、ペメトレキセドの2.0重量%よりも多くなるまで増加することはない注射溶液。容器は硬質材料、好ましくは、ガラスバイアルである注射溶液。【選択図】図1