Many researches have been performed on eye tracking technology and its major researches include mobile UI measurement, navigation, internet web measurement, measurement of TV concentration. However, a research on evaluating concentration of mobile gamer has not been performed so far. In this study, a possibility of being able to provide mobile game designer with data for concentration measurement was verified by measuring concentration of mobile gamer based on GazePlot, HeatMap, Cluster by utilizing eye tracking technology. In addition, based on the result of measuring eye tracking experiment, several advantages for objectivity, differentiation and complementarities of eye tracking technology were suggested. In order to measure suggested experiment result, an experiment was performed by using eye tracking system software (Tobii Mobile Device Stand for 2x2) and data, graph that could be utilized as reference data at the time of game development in the future were presented by identifying concentrated part and not concentrated part in playing a game after measuring concentration by each age group.