A content reproduction apparatus (1) which reproduces digital contents, and includes a device key storage unit (110) holding a device key (110a) specific to the content reproduction apparatus (1) in a manner that does not allow access from outside the content reproduction apparatus (1). The content reproduction apparatus (1), also includes a device ID storage unit (19) holding device key index information (19a) that is in a one-to-one association with a device key (110a), an instruction code receiving unit (14a) receiving an instruction code to output index information, a device key index information obtainment processing unit (10a) outputting, to outside, the device key index information (19a) stored in the device ID storage unit (19) based on the instruction, and a device key index information output processing unit (11a).