The object of this study is to analyze the background characteristics and offense characteristics of juvenile offenders who plan the offense in advance and to provide policy implications for crime prevention for juvenile offenders. For this purpose, we compared background characteristics and offense characteristics of juvenile offenders who planned the offense in advance with those of juvenile offenders who did not. Information on a total of 279 juvenile offenders arrested in five police departments in Seoul and Kyunggi areas was collected. The SPSS 22.0 program was used in analyzing the data. Major statistic methods to analyze the collective data were Chi-squares, T-test, and binary logistic regression. As a result, we found major differences between ‘planners’ and ‘opportunists’ in their background characteristics and offense characteristics, such as having delinquent friends, alcohol/drug abuse, drinking habit, respect for law, realistic plans/efforts for future, criminal history, and criminal sophistication. In addition, we found several factors that predicted juvenile offenders’ planning of the offense. Finally, we discussed limitations of the present study and made suggestions for future research.