Recently, intensive discussions about dissociative disorders have led to the rediscovery of the psychology of P. Janet, that has been under the shadow of Freud’s psychoanalysis. Nevertheless, psychiatry,“ Schulpsychiatrie”in German, has still paid little attention to the suggestion with which Janet has occupied himself throughout his long career. In this paper, the author examined suggestion from another point of view other than psychodynamic. It is presented that Freud reduced suggestion to a specific relation between an active subject and a passive object, as his precursors, F.A. Mesmer and R. de Puységur did the same. In contrast, Janet’s early studies influenced by the philosophy of M. de Biran seem to focus on another aspect of suggestion. From this aspect, suggestion is based on a spontaneous intersubjective process that should be expressed by the middle voice. Referring to H. Bergson, with whom Janet corresponded, the author pointed out that one is not always one’s own self that reflects one’s whole life history, regardless of the presence/absence of mental abnormality, as is the case with a person under suggestion. Taking into account these factors of suggestion, i. e., the middle voice and fragile selfhood that is not firmly rooted in one’s own life history, the author investigated hysteria as a distinct phenomenon that has a particularly close relation with suggestion. Furthermore, depersonalization and schizophrenia were discussed concerning their relation with hysteria. In this approach, the author suggested that the unconscious could be topographically localized not only in a deep portion of the mental apparatus, but also in its most superficial portion, unlike in the case of Freud’s psychoanalysis.