A planar display device includes: a first display panel having a plurality of first scan lines and a plurality of first signal lines; a second display panel having a plurality of second scan lines and a plurality of second signal lines; and a second selective connection circuit in which the plurality of second signal lines are categorized into a plurality of second signal line groups respectively representing different colors, with the plurality of second signal lines associated with the first signal lines in a first signal line group which are connected to a plurality of image signal supplying lines. In a case where a second display is performed by use of the second display panel, the second selective connection circuit connects all of the second signal lines to the corresponding first signal lines in the first signal line group.