Recently, the prognostic immune and nutritional index (PINI), which is calculated from the peripheral monocyte count and serum albumin level, has been reported to be useful as a prognostic marker in Korean and Chinese patients with colorectal cancer. The present study therefore examined the usefulness of the PINI as a marker for predicting the prognosis in Japanese colorectal cancer patients. A total of 529 patients who underwent curative surgery for stage I-III colorectal cancer between January 2015 and December 2019 were enrolled in this study. The PINI was calculated as [serum albumin concentration (g/dl)×0.9]-[peripheral monocyte count (mm3)×0.0007]. The median PINI was 3.242 (range=1.250-4.091). A receiver operating characteristic curve analysis revealed that the appropriate cut-off value of the PINI was 3.047. The low-PINI group had significantly lower relapse-free and overall survival rates than the high-PINI group (p<0.0001, p<0.0001, respectively). The PINI based on host factors is useful as a prognostic marker for Japanese patients with stage I-III colorectal cancer.