The present invention provides a multi-piece solid golf ball having a core, an inner cover layer and an outer cover layer. A scanning line driving circuit supplies a first voltage to the scanning lines of the display region for a predetermined period in the entire screen display mode, and supplies a second voltage to the scanning lines of the display region for a period longer than the predetermined period in the partial display mode. The last-obtained partially corrected signal is output as the reduced-crest factor signal.