A solid-state imaging apparatus comprising: imaging photodetecting means including a plurality of pixel units each of which has a photodiode to generate an electric charge in an amount according to a quantity of incident light, and a charge accumulating portion to accumulate the electric charge, said imaging photodetecting means being configured to accumulate the electric charge generated in the photodiode, in the charge accumulating portion in each of the plurality of pixel units; trigger photodetecting means including a trigger photodiode to generate an electric charge in an amount according to a quantity of incident light; output means configured to output a value according to an amount of the electric charge accumulated in the charge accumulating portion in each of the plurality of pixel units, said output means including an integrating circuit to accumulate the electric charge generated in the trigger photodetecting means, in a variable capacitance portion, and being configured to output a value according to an amount of the electric charge accumulated in the integrating circuit; controlling means configured to control the charge accumulating portions of the imaging photodetecting means whether or not to start accumulation of the electric charge and to change a capacitance value of the variable capacitance portion in the integrating circuit of the output means, based on a determinated signal generated based on the output value from the integrating circuit and indicating whether there is incident light to the trigger photodetecting means; and determinating means configured to determine whether there is incident light to the trigger photodetecting means, based on the output value from the integrating circuit, and to generate the determinated signal indicating a determinated result. imaging photodetecting means including a plurality of pixel units each of which has a photodiode to generate an electric charge in an amount according to a quantity of incident light, and a charge accumulating portion to accumulate the electric charge, said imaging photodetecting means being configured to accumulate the electric charge generated in the photodiode, in the charge accumulating portion in each of the plurality of pixel units; trigger photodetecting means including a trigger photodiode to generate an electric charge in an amount according to a quantity of incident light; output means configured to output a value according to an amount of the electric charge accumulated in the charge accumulating portion in each of the plurality of pixel units, said output means including an integrating circuit to accumulate the electric charge generated in the trigger photodetecting means, in a variable capacitance portion, and being configured to output a value according to an amount of the electric charge accumulated in the integrating circuit; controlling means configured to control the charge accumulating portions of the imaging photodetecting means whether or not to start accumulation of the electric charge and to change a capacitance value of the variable capacitance portion in the integrating circuit of the output means, based on a determinated signal generated based on the output value from the integrating circuit and indicating whether there is incident light to the trigger photodetecting means; and determinating means configured to determine whether there is incident light to the trigger photodetecting means, based on the output value from the integrating circuit, and to generate the determinated signal indicating a determinated result.