The "loss of self-evidence" has been noted by many, particularly in our country, as a fundamental dysfunction in schizophrenia. Recent recognition of this "loss of self-evidence" in personality disorders such as borderline cases, and developmental disorders such as autism and Asperger's syndrome is focusing renewed interest on this perspective. It is possible that investigation into this "loss of self-evidence" noted in the pervasive developmental disorders may provide clues into the process of its development and acquisition. This paper takes up the issue of "loss of self-evidence" illustrated through the treatment process of 2 patients (female, adulthood autism, adolescent Asperger's syndrome) the author has treated. The psychopathology of the "loss of self-evidence" seen in the pervasive developmental disorders is discussed through these cases in terms of development from the standpoint of clinical intervention for relationship disturbance. The conclusions are as follows. First, the grave psychopathology pertaining to "self-evidence" in the adult autism and adolescent Asperger's syndrome cases is discussed, wherein difficulty in controlling one's action by one's own will giving rise to serious estrangement between experience and consciousness is noted as the pathology held in common by the two. Next, through examination of the normal acquisition process of words and language, it is shown that the essence of the language disorder seen in pervasive developmental disorders lies in the acquisition of meanings of objects being based upon the absence of common experience between subject and caregiver. As such, words representing meaning and content as we see them are imprinted on such individuals, never harmonizing with their own experiential world, giving rise to serious estrangement between their experience and consciousness. Third, sharing what the child is focusing upon in the outer world and how he/she is relating to it in their experiential world, and approaching them with words appropriate to their interpretation, is pointed out as being of critical importance in the self-evidence. In support of this, it is asserted that the establishment of affective communication characterized by mutual resonance of body and affect, and the development of communication upon this basis will, for the first time, enable transmission of culture to such individuals in favorable form, emphasizing the exceptional importance of attachment formation (amae) as being the key to this process.