An assumption that ability for critical self-appraisal is a psychological prerequisite of observance of moral norms has been studied by means of learning how four different ways of negative evaluation of breaking a moral norm by a child influence his self-appraisal and his consequent observance of this norm. Sixty 6-7 years old children who persistently violated the norm of fairness participated in the experiment. It is found out that different ways of negative evaluation differently influence both the consistency of the return to the norm, and the degree of diminishing of the self-appraisal. Return to consistent observance of the norm (after a violafion of it) is always preceded by deteriorated self-appraisal.