To reduce power consumption, a data transmission apparatus comprises: a memory; a timing instruction unit which indicates a start timing of outputting data from the memory; a first interface which outputs data stored in the memory according to the timing instruction unit; a second interface which transfers the data from the first interface to a buffer; and a control unit which issues a command to perform transition of the first interface and the second interface to a power saving state based on the data output start timing indicated by the timing instruction unit, and a sum of a time required to perform transition of the first interface and the second interface to the power saving state and a time required to return from the power saving state.