One of the symptoms of a schizophrenic patient is a hallucination. Schizophrenic patients with hallucinations tend to have a problem with their ability to correct them. In writing this journal researchers provided data on group activity therapies. The purpose of this study is to find out how effective group activity therapy is to treat the hallucinations of schizophrenic patients in the mental hospital of Prof. Dr. Soerojo Magelang. The data collection method for this research was interview and observation, with 2 subjects with the initials SU and IYN. The analysis conducted in this research is a descriptive qualitative. The result of group activity therapy for subject 1 changes in the activation, socialization, ability to recognize hallucinations, rebukes, and listening skills. Whereas the results of subject group activity therapy 2 are changing in activation indicators, the ability to recognize hallucinations, and the ability to rebuke. Group activity therapies can increase the ability to rebuke hallucinations on both subjects, but they are affected by other therapies such as pharmacology and rehabilitation.