This study investigated the relationships between meta-cognitive strategies and second language (L2) knowledge on L2 reading ability and analyzed the role of meta-cognitive strategies as ‘self-regulatory mechanism’. A total of 108 third-year middle school students participated in this study, and their meta-cognitive (global, problem-solving, support reading) strategies, L2 knowledge (vocabulary and grammar), and L2 reading ability were analyzed. The results shows that support strategies, problem-solving strategies, and L2 vocabulary knowledge significantly influenced the L2 reading ability in the entire participant group. However, there were differences between the two level groups (higher and lower): In the higher group, support reading strategies had a significant effect on L2 reading, while in the lower group, there were no significant variables, and the higher the support and problem-solving strategies were, the lower the L2 reading ability was. In conclusion, meta-cognitive strategies are an important knowledge resource for L2 reading. Therefore, to promote self-regulated L2 learning ability in middle school, it is necessary to repeat training for automatic use of meta-cognitive strategies based on cognitive knowledge resources necessary for successful L2 reading.