A detecting device is configured to detect a discharge state of droplets from a discharging head configured to discharge droplets onto a medium. A detecting device includes an irradiation unit configured to irradiate the medium on which a predetermined pattern is recorded with the droplets with irradiation light, and to scan the medium with the irradiation light in a scanning direction, a light-receiving unit configured to receive reflected light which is the irradiation light reflected by the medium, and to output a signal indicating intensity of the reflected light, and a control unit configured to perform determination process for determining a discharge state of the droplets onto the medium by using intensity change of the reflected light in scanning the predetermined pattern in the scanning direction.