Objectives: This pilot study examined the preliminary findings associated with a cognitive-load-controlled structured psychodrama program on affect, fear of negative evaluation, and general psychopathology in long-term psychiatric inpatients, most of whom had schizophrenia spectrum disorders. Methods: A single-group pre-post design was used. A total of 125 stabilized long-term psychiatric inpatients participated in a 25-session structured psychodrama program. To enhance measurement validity in consideration of participants’ cognitive characteristics, self-report measures were administered in small-group sessions with individualized explanation. Primary outcomes (Positive and Negative Affect Schedule [PANAS], Affect Balance Scale [ABS], and Brief Fear of Negative Evaluation [BFNE]) were assessed in 125 participants, and the secondary outcome (Brief Psychiatric Rating Scale [BPRS]) was assessed in a randomly selected subgroup of 53 participants. Results: After the intervention, positive affect significantly increased, whereas negative affect significantly decreased on both the PANAS and ABS (all p＜0.001). BFNE scores significantly decreased from 43.14 to 28.94 (p＜0.001). Total BPRS scores also significantly decreased from 47.49 to 34.76 (p＜0.001), with notable improvements in depressive mood, anxiety, tension, somatic concern, and emotional withdrawal. Conclusion A structured psychodrama program may be a feasible and potentially beneficial psychosocial intervention for long-term psychiatric inpatients. However, given the single-group pre-post design and other methodological limitations, the magnitude of the observed changes should be interpreted cautiously. These findings may serve as preliminary data for future controlled trials.