In the case where a previous character (P1) is cleared on a screen (20) and a new character (P2) is displayed on the right of the previous one, first, image data to be transferred (P2) is prepared in a source image memory. Next, a write start address (W) is set at the head of a bit sequence of a left clearance width (LC)×BPP, which precedes the destination address (T) of a frame buffer into which the head (S) of the image data (P2) is to be written. After that, a series of burst transfer repeatedly copies clearance data held in a register into a region of the left clearance width (LC), starting from the write start address (W), and subsequently writes one line (a transfer width (W1)×BPP) of the image data (P2). The write start address is incremented by a frame width (FW)×BPP.