Interprofessional collaboration (IPC) for older patient care among family physicians, dentists, therapists, nutritionists, nurses, and pharmacists in the rural hospital care of older patients could improve the hospital readmission rate. However, there is a lack of interventional studies on IPC for improving the readmission rate among Japanese older patients in rural hospitals. This quasi-experimental study was performed on patients >65 years who were discharged from a rural community hospital. The intervention was IPC implementation with effective information sharing and comprehensive management of older patients' conditions for effective discharge and readmission prevention; implementation started on 1 April 2021. The study lasted 2 years, from 1 April 2021 to 31 March 2022 for the intervention group and from 1 April 2020 to 31 March 2021 for the comparison group. The average participant age was 79.86 (standard deviation = 15.38) years and the proportion of men was 45.0%. The Cox hazard model revealed that IPC intervention could reduce the readmission rate after adjustment for sex, serum albumin, polypharmacy, dependent condition, and Charlson Comorbidity Index score (hazard ratio = 0.66, 95% confidence interval: 0.54-0.81). Rural IPC intervention can improve inpatient care for older patients and decrease readmission rates. Thus, for effective rural IPC interventions, family physicians in hospitals should proactively collaborate with various medical professionals to improve inpatient health outcomes.