A master device configured to establish communication with at least one slave device via a bus, the master device being an Improved Inter Integrated Circuit master device and the slave device being an Improved Inter Integrated Circuit slave device; the master device comprising: an acquisition unit configured to acquire, from the at least one slave device, a max transfer length indicating a maximum transfer length that the at least one slave device is transferable in one data transfer; a transmission/reception control unit configured to control transmission/reception of data so that data to be transferred in one data transfer has a data length equal to or shorter than the max transfer length in data transfer to/from the at least one slave device; and a transmission unit configured to transmit an index for notifying an initial address from which read out of the data is started, and transfer length information indicating the data length of the data to be transferred, prior to data transfer of the data on a basis of the index and the transfer length information, wherein when read transfer of reading out data from the at least one slave device is performed, the acquisition unit acquires a max read length that is the max transfer length in the read transfer by the at least one slave device, the transmission/reception control unit, in a case where data having a data length equal to or longer than the max read length is requested to be transferred, instructs the slave device to control transmission/reception of data requested to be transferred by dividing the data to have a data length equal to or shorter than the max read length, and transmitting the data through a plurality of transmissions, and the transmission unit transmits the transfer length information indicating a data length of entire data requested to be transferred only once. an acquisition unit configured to acquire, from the at least one slave device, a max transfer length indicating a maximum transfer length that the at least one slave device is transferable in one data transfer; a transmission/reception control unit configured to control transmission/reception of data so that data to be transferred in one data transfer has a data length equal to or shorter than the max transfer length in data transfer to/from the at least one slave device; and a transmission unit configured to transmit an index for notifying an initial address from which read out of the data is started, and transfer length information indicating the data length of the data to be transferred, prior to data transfer of the data on a basis of the index and the transfer length information, wherein when read transfer of reading out data from the at least one slave device is performed, the acquisition unit acquires a max read length that is the max transfer length in the read transfer by the at least one slave device, the transmission/reception control unit, in a case where data having a data length equal to or longer than the max read length is requested to be transferred, instructs the slave device to control transmission/reception of data requested to be transferred by dividing the data to have a data length equal to or shorter than the max read length, and transmitting the data through a plurality of transmissions, and the transmission unit transmits the transfer length information indicating a data length of entire data requested to be transferred only once.