The new adult guardianship system was introduced, instead of declaration of legal incapacity regime, to provide a legal tool for supporting decision-making for persons with impaired decision making ability. For such disabled persons, it would be best to live integrated within communities without resort to guardianship. For such a goal to materialize, members of communities should develop alternative communication tools and methods to facilitate communication with persons with impaired decision making ability, lawyers should create and prepare various kinds of trusts, advance directives to medical treatment and other activities, various types of contractual guardianship forms, delegation contract forms and representation forms in order to supplement insufficient capacity of such disabled persons for supply of goods and services. Impairment to decision making ability is not unfortune occurring to exceptional scope of person, but probable risk to all of us living in the aged society and risk producing society, which we must not overlook The least and negative measures which can be taken to guarantee human dignity of such disabled persons are to ensure that the commencement of guardianship need not incur disqualification of legal rights and power and depriviation of legal capacity of litigation. What is required is to ensure that any persons who lack sufficient capacity to make decisions, whether or not resorting to guardianship, are entitled to access to and participate in legal proceedings. This article proposes that incapacity of litigation is to be decided in accordance with individual capacity to make decision on specific matters, furthermore, it proposes that even those who lack capacity of litigation should easily access to and participate in the legal proceedings by a litigation friend.