In a network of an IEEE 1394 system or the like, a data transmission rate can be properly controlled by an apparatus to receive the transmitted data. An apparatus for transmitting data is set as a first apparatus and each of one or more apparatus for receiving the transmitted data from the first apparatus is set as an external apparatus. The number of the external apparatuses to which the data are to be transmitted is indicated. A transmission speed is varied upon receipt of a control command from one of the external apparatuses to which a control right is given. The control right is returned when the control command is not given from the external apparatuses to which the data are transmitted for a predetermined period of time. The control right is returned to the first apparatus if there are a plurality of apparatuses to receive the data from the first apparatus.