Action of the principles of the organization and prosecutor's office activity, and also the main beginnings of criminal proceedings on public prosecutor's supervision of observance of laws at application of measures of restraint in pre-judicial investigation is analyzed. Main of them who have the greatest impact on public prosecutor's supervision of legality of application of measures of restraint in pre-judicial investigation are allocated and characterized. Concrete manifestations of realization of these principles are considered. Their general meaning for public prosecutor's supervision of observance of laws at application of measures of restraint is established. Theoretical and standard gaps concerning compliance of implementation of public prosecutor's supervision in this sphere to the considered principles come to light. Scientifically reasonable recommendations concerning increase of efficiency of participation of the prosecutor in application of institute of measures of restraint in pre-judicial criminal proceedings are made.