Recently self-injurious behavior including wrist-cutting among youth has been a serious problem in Japan.Self-injury is the act to injure oneself deliberately without a suicidal intent, by a nonfatal method, predicting a nonfatal consequence. It is frequently repeated to cope with distress, for instance, to reduce an intolerable and painful feeling.
 Self-injury is the act to be differentiated from suicide,and often cause a negative attitude in mental health professionals, although many previous studies reveal that individuals with self-injury are more likely to death by suicide than those without, and that self-injury may be one of the important risk factors predicting future suicide.
 In this paper, the author gives an outline of understanding and treating self-injury, and indicates that to support and care self-injuring youth by mental health professionals may contribute to suicide prevention in adolescence.