The present invention relates to a photo-detecting apparatus capable of obtaining the intensity distribution of incident light at the same timing even when the intensity distribution of incident light may change with time. The photo-detecting apparatus comprises a photo-detecting section in which plural pixels are arranged in a two-dimensional array, and a signal processing section. Each of plural pixels constituting the photo-detecting section has a first photodiode and a second photodiode, N first photodiodes included in the group of pixels constituting the m-th row of the two-dimensional array being electrically connected to each other through multiple lines, while M second photodiodes included in the group of pixels constituting the n-th column of the two-dimensional array being electrically connected to each other through other multiple lines. The signal processing section includes M first readout circuits and N second readout circuits, and the signal processing section transfers an electric charge generated in the first photodiodes connected to the multiple lines into the first readout circuits to output voltage values in accordance with the charge quantity in the respective first readout circuits, while transferring an electric charge generated in the second photodiodes connected to the other multiple lines into the second readout circuits to output voltage values in accordance with the charge quantity in the respective second readout circuits.