A liquid ejecting apparatus includes an ejection unit that ejects a liquid, a medium support unit that has a support face supporting a medium to which the liquid is ejected, an irradiation unit that irradiates the medium with a first electromagnetic wave from an oblique direction with respect to the support face, and a sensor that detects a second electromagnetic wave which is emitted from an irradiation region of the first electromagnetic wave on the support face, in which the sensor is in a position with respect to the irradiation unit which is the same side as an irradiation direction of the first electromagnetic wave, and is arranged in a position where a regular reflection component of the first electromagnetic wave reflected at a peak spot where irradiation energy of the first electromagnetic wave peaks in the irradiation region is not detected.