An image generating apparatus includes a timepiece determining section determining whether or not the setting of an internal clock is normal, a certificate determining section determining whether or not a received electronic certificate from a communication target apparatus is valid based on the setting of the internal clock, a communication section performing communication for authentication with the communication target apparatus if the certificate determining section determines that the received electronic certificate is valid and receiving image information from an image supplying apparatus belonging to a network to which the communication target apparatus belongs or the communication target apparatus, a control section making the communication section perform communication for authentication irrespective of whether or not the received electronic certificate is valid if the timepiece determining section determines that the setting of the internal clock is not normal, and an image generating section generating an image based on the image information.