An estimation method includes: generating information regarding success or not success in a connectivity checking test between “N” nodes in a case in which a failure occurs in a verification target path including the nodes, the information being generated as pattern information for each failure location; selecting “M” network devices from among a plurality of network devices in accordance with occurrence of the failure; executing the connectivity checking test between the selected network devices; comparing a checking result of the connectivity checking test with pattern information that satisfies “N=M” in the pattern information; and estimating the failure location in the service path based on the failure location associated with the pattern information in a case in which the pattern information that satisfies “N=M” matches the checking result.