The accessory apparatus includes an accessory communicator providing, with an image-capturing apparatus, three channels that are a notification channel, a first data communication channel and a second data communication channel. The image-capturing apparatus and the accessory apparatus are each configured to have a function of switching the second data communication channel between a first setting in which the data transmission from the image-capturing apparatus to the accessory apparatus is allowed and a second setting in which data transmission from the accessory apparatus to the image-capturing apparatus is allowed, The accessory controller is configured to, in response to receiving from the image-capturing apparatus through the notification channel a first notice indicating completion of switching from the first setting to the second setting in the image-capturing apparatus, switch from the first setting to the second setting in the accessory apparatus.