Following statistical methods were adapted in this study, in order to standardize the concepts of the Degree of Delinquency (DD), for 107 juvenile elinquent boys. (1) The Principal Component Analysis (PCA) was administrated among Indices Related to DD (IRDD) composing of 25 sub-categories which had been extracted from 90 sub-categories in 6 dimensions of DD. (2) The Multiple Regression Analysis (MRA) was administrated by using rating score for DD (criterion variable) and 18 rating scores for each of IRDD explanatory variables). (3) MRA was also administrated by using rating score for Prediction of the Occurrence of Crime and Delinquency (POCD) (criterion variable) and 18 rating scores for each of IRDD (explanatory variables). (4) Correlation coefficients between DD scores and rating scores for DD, between DD scores and rating scores for POCD, and between rating scores for DD and rating scores for POCD, were calculated, respectively. Main findings based on analyses mentioned above, were as follows; (1) The 1st component consisted of 7 IRDD, and its reliability coefficient was .8762. (2) Psychological meanings of 1st principal component were assumed to associate with “tendencies to indulge in pleasure, and to float.” (3) In addition to 7 IRCD, 1 IRDD was extracted on the bases of the results from the MRA. It might be given as a conclusion that 7 IRDD and 1 additional IRDD would be utilized as items of single delinquency scale, if we could understand the meanings of DD in unified form mentioned above (2).