Metacognition is a process of self-regulation based on confidence in the internal information of own, such as memory and knowledge. In animal studies, researchers focused on a behavior which should be the index of metacognition in a situation where metacognitive behavioral control gives more reinforcement. Already it is known that in some types of primates metacognitive control of behavior is demonstrated. Rodents would be a useful model for the neural mechanisms and molecular basis of the metacognition. However, behavioral demonstrations of metacognition in rodents up to now produced inconsistent results. This study tried to fix procedural problems of existing studies and examined whether rats show the behavioral control based on own memory. In this experiment, delayed matching to sample task was utilized. The task had been modified by an addition of an option that showed the correct choice. This option made the current trial easy but at the same time decreased reward amount. This option was available only before the presentation of alternative choices. Therefore, rats decide whether to use that option only by confidence to own memory for sample stimulus. If rats have metacognition, rats use that option only when confidence is low. Comparing two conditions that rats can use that option or not, accuracy and the amount of acquisition reward should significantly be higher and larger in option available condition. We also confirmed whether metacognitive option use generalized to the sample omission test. As a result, three rats exhibited higher accuracy in the option available condition, and two rats used more of that option in the sample omission trials. Results suggest that rats have metacognition. The establishment of metacognitive behavior in rats can expand the neuro scientific study of animal metacognition. (Work supported by a Grant-in-aid for Scientific Research from JSPS, The Adolescent Brain, # 23118001).