The invention provides a display device which can suppress a bending repulsive force of a flexible printed circuit board having a folded portion thus reducing a manufacturing cost thereof. In a display device which includes a display panel, and a flexible printed circuit board which has one end thereof connected to a terminal portion of the display panel, the flexible printed circuit board includes a base member, a line layer which is formed on the base member using a metal layer, a surface protective cover which covers the line layer, and a folded portion, the line layer includes a signal line which supplies control signals or display data to the display panel and a dummy line, the signal line is covered with the surface protective cover at the folded portion, and the folded portion includes at least one exposed portion in which the dummy line is exposed from the surface protective cover ranging from a folding start point to a folding finish point.