The study was undertaken to explore the ways to vitalize and develop the sandplay therapy by verifying the effect and influence of sandplay therapy used in school counseling of emotional and behavioral problems in youth. The subjects were 20 students from Seoul G Junior High School. The characteristics of their problems were emotional ones like distractedness, lethargy, depression or anxiety and behavioral ones like school maladjustment, drinking, smoking, runaways, violence, or stealing. The Therapy for the subjects continued from March 26, 2012 to Nov.14, 2014; the sessions were conducted one-on-one, once a week for 45 minutes of class time, starting from at least 10 sessions to 66 sessions at the most. The method of research was to compare the pre- and post scores of MMPI-A(Minnesota Multiphasic Personality Index for Adolescents) and K-CBCL(Korea-Child Behavior Checklist). The results are as follows. First, sandplay therapy is effective in solving internalized and emotional problems in adolescents. Second, sandplay therapy is effective in reducing anti-social behavior or externalized problems of adolescents. Third, sandplay therapy is effective in forming positive relationships in the community, school, and homes and improving their social skills. Fourth, sandplay therapy is effective in helping their inner maturing and to nurture the growth of their ego. Therefore, using sandplay therapy in school counseling is expected to work positively when dealing with emotional and behavioral problems of youth.