Provided is a light detecting apparatus including: a phase locked loop portion that generates a sampling clock based on a synchronization signal output from a light source that emits pulsed laser light; an A/D convertor that performs sampling of signal light output from a sample as a result of radiating the laser light thereon in accordance with the sampling clock; and a received-data processing portion that accommodates, every time N items of the sampling data are continuously acquired, the N items of data in a single data sequence. The phase locked loop portion is provided with a clock generating portion that generates a clock that has a frequency that is N times a pulse frequency of the laser light and that is synchronized with a phase of the laser light, and a delay adjusting portion that generates the sampling clock by adjusting a delay amount of the generated clock.