Introduction: We investigated a protocol to support the treatment of constipation that was developed in collaboration with physicians and the effectiveness of Protocol Based Pharmacotherapy Management (PBPM) performed by pharmacists in improving constipation.Methiod: Patients with constipation who underwent PBPM between August 2020 and May 2021 were included in this study. The results of the Constipation Scoring System (CSS) and the Bristol Stool Form Scale (BSFS) assessments by pharmacists on the first day of intervention and at discharge were collected retrospectively to evaluate the efficacy of PBPM. Wilcoxon's signed rank test was used for statistical analysis, and the threshold value for rejecting the null hypothesis was p < 0.05.Results: Of the 23 eligible patients, three were excluded according to the criteria, and 20 patients were included. Median CSS improved significantly from 11.5 points [8.25-16.75] at the first intervention to 5.5 points [2.75-10.25] at discharge. The median BSFS improved significantly from Type 2 [2-3] to Type 3.5 [3-4]. Conclusion: PBPM by pharmacists to support the treatment of constipation resulted in improvement of constipation.