A spatial information detecting device is provided, which is capable of reducing the possibility that a
saturation phenomenon is caused by the influence of an environmental light. This device includes a photoelectric converting portion for receiving a
signal light from a target space to generate electric charges, a charge separating portion for separating electric charges corresponding to a constant amount of a bias component as undesired electric charges from the electric charges generated by the photoelectric converting portion, a charge accumulating portion for accumulating the remaining electric charges as effective electric charges reflecting a fluctuation component of the
signal light, a barrier control
electrode for forming a potential barrier between the charge separating portion and the charge accumulating portion, and a charge take-out portion for outputting the effective electric charges as an received-light output. By controlling a
voltage applied to the barrier control
electrode to change a height of the potential barrier, it is possible to adjust an amount of electric charges flowing from the charge separating portion into the charge accumulating portion over the potential barrier.