Abstract: 9.5% of the harmful acts of schizophrenics is evaluated as diminshed responsibility. Through analysis the reasons that should be so are as follows: 1. The illness has been fundamentally remitted, but the emotional instability still remains and the self—control is weakened. 2. The illness has not been fully remitted and the residuary symptoms still exists. 3. The symptoms of the illness are remarkbly emerging while the offence is committed, but there is no relationship of cause and effect between the illness and the offence. For the time being, however, what is actually the evaluaion of diminished responsibility based on and how to master the rules are left over for further explorations. The forensic psychiatrists should sum up an objective law as well as a practicable norm which will be available to raise the level of legal expertise.