In advance care planning (ACP), there are cases where it is difficult for patients to express their intentions for various reasons. In this study, we discussed the difficulties and countermeasures for the implementation of ACP in the cases of children and the elderly, involuntary hospitalization for psychiatric care, and the choice of end-of-life nutrition, as cases in which it is difficult for the patients to express their intentions. Internal difficulties caused by the individual, external difficulties such as non-provision of appropriate information and social difficulties such as the absence of significant others were considered to be the factors that make ACP implementation difficult. It is important for supporters to understand these difficulties and to implement ACP according to the individual patients. It is hoped that discussions on the promotion of ACP will be further enhanced in the future.