The present invention provides a method for determining the likelihood of colorectal cancer development in a human ulcerative colitis patient, the method including: a measurement step of measuring methylation rates of one or more CpG sites present in specific differentially methylated regions in DNA recovered from a biological sample collected from the human ulcerative colitis patient； and a determination step of determining the likelihood of colorectal cancer development in the human ulcerative colitis patient based on average methylation rates of the differentially methylated regions which are calculated based on the methylation rates measured in the measurement step and a preset reference value or a preset multivariate discrimination expression, in which the reference value is a value for identifying a cancerous ulcerative colitis patient and a non-cancerous ulcerative colitis patient, which is set for the methylation rate of each differentially methylated region, and the multivariate discrimination expression includes, as variables, average methylation rates of one or more differentially methylated regions among the specific differentially methylated regions.
