An authentication method, in a household device authentication system including a first controller (A, B) connected to a first server via a first network, a second controller (B, A) connected to a second server via a second network, and a device (C) connected to the first controller (A, B) and the second controller (B, A), the authentication method including performing authentication between the device (C) and the first controller (A, B) or between the device (C) and the second controller (B, A), the authentication method comprising: an authentication step of acquiring (S134), by the device (C), a first certificate revocation list from the first controller (A, B), the first certificate revocation list including first time information indicating a next issue date of the first certificate revocation list; acquiring (S134), by the device (C), a second certificate revocation list together with a certificate revocation list update request from the second controller (B, A), the second certificate revocation list including second time information indicating an issue date of the second certificate revocation list; comparing (S137), by the device, the first time information and the second time information thereby determining whether the first controller is invalid or not, wherein the first certificate revocation list and the second certificate revocation list each are a revocation list associated with a certificate of the first controller (A, B), a certificate of the second controller (B, A), and a certificate of the device (C), wherein in the authentication step, in a case where the first time information is earlier than the second time information, it is determined that the first controller is invalid, and wherein the first certificate revocation list is received from the first controller (A, B) before the second certificate revocation list form the second controller (B,A) and the first certificate revocation list is recorded by the device (C). an authentication step of acquiring (S134), by the device (C), a first certificate revocation list from the first controller (A, B), the first certificate revocation list including first time information indicating a next issue date of the first certificate revocation list; acquiring (S134), by the device (C), a second certificate revocation list together with a certificate revocation list update request from the second controller (B, A), the second certificate revocation list including second time information indicating an issue date of the second certificate revocation list; comparing (S137), by the device, the first time information and the second time information thereby determining whether the first controller is invalid or not, wherein the first certificate revocation list and the second certificate revocation list each are a revocation list associated with a certificate of the first controller (A, B), a certificate of the second controller (B, A), and a certificate of the device (C), wherein in the authentication step, in a case where the first time information is earlier than the second time information, it is determined that the first controller is invalid, and wherein the first certificate revocation list is received from the first controller (A, B) before the second certificate revocation list form the second controller (B,A) and the first certificate revocation list is recorded by the device (C). <EOS>