A low-power-consumption active matrix display device is provided.A driving method of an active matrix display device having M gate lines and N source lines, comprises the steps of writing a data signal of an (m-1)-th row (2.ltoreq.m.ltoreq.M, m is a natural number) to the source line, comparing a data signal of an m-th row with the data signal of the (m-1)-th row before the data signal of the m-th row is input to the source line, electrically disconnecting source lines to which a data signal of the m-th row is input from a power source circuit in the case where the data signal of the m-th row is different from the data signal of the (m-1)-th row, electrically connecting source lines of which a data signal of the m-th row is different from a data signal of the (m-1)-th row out of the N source lines to one another, and electrically disconnecting the connected source lines respectively and connecting them to the power source circuit so that the data signal of the m-th row is written to the source line.