This invention can reduce the circuit scale by synthesizing OSD data to be superposed on a picture of each resolution by using common OSD data. According to this invention, a video resolution converter converts an HD (High Definition) video signal into an SD (Standard Definition) video signal such as an NTSC or PAL video signal. A memory controller receives a sync signal identical to an SD picture obtained by frequency-dividing an HD video signal, and a sync signal based on an SD video signal, and reads out OSD data (4 bits per pixel) from the memory on the basis of these sync signals. The OSD data read out on the basis of the SD video signal is synthesized with the SD video signal by an SD_OSD_MIX unit, and then output. The OSD data read out on the basis of the SD sync signal synchronized with the HD is multiplied by an integer by an OSD resolution converter, synthesized with an HD video signal by an HD_OSD_MIX unit, and then output.