Provided is a light source apparatus detecting, even when a minute crack occurs in a fluorescent material plate, such a defect to take a safety measure. The light source apparatus includes a laser light source emitting laser light, a fluorescent material plate including a laser light irradiation region and being capable of emitting light by irradiating the laser light irradiation region with laser light to convert the light in wavelength, a light scanning mechanism capable of scanning the laser light irradiation region with the laser light, and a transparent conductive film pattern disposed on the fluorescent material plate in the laser light irradiation region and including a parallel wiring portion in a first direction. The interval between adjacent portions of the transparent conductive film pattern in a second direction intersecting the first direction changes along the second direction depending on a portion which is located within the pattern.