The degree of an influence from wiring crosstalk between signal lines of a data signal transmission line (video signal line) is decided on the basis of an input signal generated in display controlling unit (a timing controller) at a predetermined timing (at each frame period, at each clock pulse period, or at each horizontal period) and, based on a result of the decision, the voltage amplitude of a data signal is adjusted so that it may exceed an input amplitude specification value for data line driving circuits (data drivers) by a predetermined value.