An optical sensing apparatus including a light sensor, a plurality of light-emitting devices, and a controller is provided. The light sensor is disposed on a substrate. The light sensor senses a light reflection signal in a sensing area of the optical sensing apparatus. The light-emitting devices are disposed on the substrate and around the light sensor. The light-emitting devices provide an optical signal to be transmitted into the human tissue. Then, the optical signal is reflected by the human tissue to generate the light reflection signal. The controller determines whether the position of the human tissue has been changed in the sensing area. The controller drives at least one light-emitting device of the light-emitting devices and adjusts the light intensity thereof to provide the appropriate optical signal. Besides, a measuring method of the optical sensing apparatus is proposed.