This paper proposes a model explaining both the development and occurrence of delinquency and crime from the perspective of attachment theory. First of all, factors regarding the development of delinquency and crime are summarized, which includes attachment, and then their interactions especially at the onset of delinquency in adolescence are discussed. Then, the relationship between individual differences of attachment and offenses, such as sexual crime, violent crime, and drug abuse, are reviewed. It was concluded that each delinquent behavior connotes deviant forms of both attachment behaviors and attachment figures, that is, such actions relieved offenders from afraid, and in that sense, their actions were thought of as solutions, not problems. The Dual Circle Model of development and occurrence of delinquency and crime are presented as a contribution to the forensic field based on this information. Finally, a comparison with preexisting theories is discussed mainly regarding rehabilitation intervention. Future tasks and prospective studies are also suggested.