The present invention provides a combination of genes useful for information which can be used for the prediction of postoperative recurrence of gastric cancer and the acquisition of the information, a probe detecting these genes and a primer set for PCR, a method for detecting these genes using the primer and the primer set and a method for obtaining the information which can be used for the prediction of recurrence. Information useful for the prediction of postoperative recurrence can be obtained by determining the presence or absence of gastric cancer cells which show a possibility of postoperative recurrence in a sample such as an peritoneal wash collected from a patient by detecting a particular gene specific to gastric cancer cells or a gene product thereof.