Background: The Ineffective health management and adherence are the problems of mentally ill patient, thus if they left untreated, they could create major disadvantageous for client themselves, family, community even goverment. Objective: the aim of this case study was to identify the effect of Acceptance and Commitment Therapy (ACT) on client with Ineffective health management and to identify adherence, acceptance and commitment of regiment. Materials and Methods: The research approach used in this  study was case study conducted on 5 respondents consist of mentally ill patient with Ineffective health management. The ACT were given for 4 sessions through two to four meetings, and evaluated for three weeks. After the ACT intervention, client were measured and analysed. Client were measured use  MARS (Medication Adherence Rating Scale) Results: After the client were given ACT and nursing intervention, the adherence increased 71% (14 points), the acceptance ability and commitment increased into  70% on five clients with Ineffective health management. Medication adherence, acceptance and commitment level were lower on the younger clients, client who gets stigma from closest relatives and client with lack of family support. Conclusion: this study recommended ACT to increase the health management on mentally ill patient as the approach to increase adherence and commitment on treatment.