Authentication collaboration system and id provider equipment

An ID provider device according to an embodiment includes a policy information storage unit that stores policy information representing a user of a target to whom transmission of service data is permitted, an authentication collaboration request preliminary processing unit that performs a policy evaluation process and an account collaboration process at a timing according to a log-in status of a user terminal when an authentication collaboration request is received, and an authentication collaboration request transfer unit that transfers the authentication collaboration request to the authentication collaboration request preliminary processing unit when the authentication collaboration request is received from the service provider device.