This study has focused on the limitation of preceded studies about juveniles' repeated delinquency. The preceded studies have not deeply touched on the processed duration between the first and the second delinquency. In particular, this limitation has been a sort of barrier intervening for the delinquent juveniles on the level of social work practice. This study has been designed to examine the process of steeping in the second delinquency, then to find out some methods of social work intervention. For this study, 10 juveniles incarcerated in four reformatories have been interviewed in depth about their lives before arrested because of the second delinquency. The collected data has been analysed on the basis of the Grounded Theory method developed by Anselm Strauss and Juliet Corbin. The analysed data has been resulted that “the juveniles have been steeped in delinquency trying to adjust socially in difficult circumstance.” The delinquent juveniles have been classified in three types; ‘a resentment type’, ‘an anger type’, and ‘an earnest type’. For resonable rehabilitation of the repeated delinquent juveniles, the following suggestions are available. Firstly, the juveniles have to prepare throughly in reformatory before getting back home. Secondly, the juveniles who are in difficulty personally have to be served enough time in halfway house. Thirdly, some programs must be served to the juveniles to build positive relationships with neighbors including families and friends. Fourthly, continuous programs should be served to the juveniles according to the each types of repeated delinquent juveniles.