A conventional data communication apparatus cannot set different receiving capacity for each type of received image data. To solve this problem, a data communication apparatus according to this invention notifies a partner apparatus of the receiving capacity in the normal reception mode of the apparatus at the start of communication. If high-quality transmission is designated for image data transmitted from the partner apparatus, the data communication apparatus determines whether the image data exceeds its own receiving capacity in the high-quality reception mode. If the image data does not exceed the receiving capacity in the high-quality reception mode, the data communication apparatus performs high-quality reception/recording; otherwise, notifies the partner apparatus of its own receiving capacity in the high-quality reception mode.