Provided is a depth information measuring method and apparatus for a three-dimensional (3D) camera. The depth information measuring method and apparatus may output, to an object, an optical pulse of which an intensity is higher than an intensity of an ambient light. The depth information measuring method and apparatus may generate a voltage that is proportional to a log value of an intensity of a light reflected from the object. The depth information measuring method and apparatus may use discharging units, and the discharging units may respectively include dischargers having different discharging speeds or capacitors having different capacities.