A coating apparatus for conducting coating by discharging liquid droplets onto a substrate, is provided with a discharging head having an external terminal to receive control signals and a plurality of nozzles to discharge liquid droplets in response to the control signals; a drive control board to output the control signals to the discharging head; a cable to transmit the control signals from the drive control board to the discharging head; a relay board having a first terminal to form a first joint section to joint with the external terminal of the discharging head and a second terminal to form a second joint section to joint with the cable; and an intercepting member to intercept contact between the first joint section and outside air and to intercept contact between the second joint section and outside air.