A satellite signal receiving device having a receiver circuit that receives a satellite signal transmitted from a positioning information satellite, comprising: a solar cell that converts light energy to electrical energy; a generating state detection circuit (43, 44) that detects the generating state of the solar cell; and a control circuit that controls the receiver circuit and the generating state detection circuit, sets a threshold value for determining if the illuminance of light on the solar cell is a high illuminance state greater than or equal to a preset illuminance threshold level, or a low illuminance state lower than the illuminance threshold level, compares a detection value detected by the generating state detection circuit (43, 44) with the threshold value and operates the receiver circuit if a high illuminance state is determined, characterized in that in a first alternative the detection value detected by the generating state detection circuit (43, 44) is an output value of the solar cell; and the control circuit compares the solar cell output value and the threshold value and operates the receiver circuit when a high illuminance state is determined, and resets the threshold value so that the illuminance threshold level becomes higher if reception of the satellite signal by the receiver circuit failed, or in a second alternative, when determining a high illuminance state or low illuminance state by comparing the solar cell output value and a specific value set according to the illuminance threshold level, the detection value detected by the generating state detection circuit is a power generating evaluation time, which is the time the solar cell output value is continuously in the high illuminance state; and the control circuit operates the receiver circuit when the power generating evaluation time is greater than or equal to a preset threshold value, and resets the threshold value longer if reception of the satellite signal by the receiver circuit failed. a solar cell that converts light energy to electrical energy; a generating state detection circuit (43, 44) that detects the generating state of the solar cell; and a control circuit that controls the receiver circuit and the generating state detection circuit, sets a threshold value for determining if the illuminance of light on the solar cell is a high illuminance state greater than or equal to a preset illuminance threshold level, or a low illuminance state lower than the illuminance threshold level, compares a detection value detected by the generating state detection circuit (43, 44) with the threshold value and operates the receiver circuit if a high illuminance state is determined, characterized in that sets a threshold value for determining if the illuminance of light on the solar cell is a high illuminance state greater than or equal to a preset illuminance threshold level, or a low illuminance state lower than the illuminance threshold level, compares a detection value detected by the generating state detection circuit (43, 44) with the threshold value and operates the receiver circuit if a high illuminance state is determined, characterized in that in a first alternative the detection value detected by the generating state detection circuit (43, 44) is an output value of the solar cell; and the control circuit compares the solar cell output value and the threshold value and operates the receiver circuit when a high illuminance state is determined, and resets the threshold value so that the illuminance threshold level becomes higher if reception of the satellite signal by the receiver circuit failed, or in a second alternative, when determining a high illuminance state or low illuminance state by comparing the solar cell output value and a specific value set according to the illuminance threshold level, the detection value detected by the generating state detection circuit is a power generating evaluation time, which is the time the solar cell output value is continuously in the high illuminance state; and the control circuit operates the receiver circuit when the power generating evaluation time is greater than or equal to a preset threshold value, and resets the threshold value longer if reception of the satellite signal by the receiver circuit failed.