A display device includes a display panel including first and second panel pads electrically connected to each other, a connection board including first and second connection board pads connected to the first and second panel pads, respectively, an output pad, and a driving circuit. The driving circuit includes a pull-up resistor connected between a first voltage terminal and a first node, and a comparator configured to compare a voltage at the first node with a reference voltage and to output a contact test signal corresponding to a comparison result to the output pad. The first connection board pad is electrically connected to the first node, and the second connection board pad is connected to a second voltage terminal.