An imaging apparatus comprising: a photoelectric conversion unit configured to generate a charge based on photoelectric conversion; and an AD converting unit configured to generate a digital signal, including a comparing circuit; a counter circuit configured to generate a count signal by performing a counting operation; a ramp signal generating circuit configured to output a plurality of ramp signals; and a selecting circuit, characterized in that the comparing circuit is configured to generate a first comparison result signal by performing a reference comparison between a signal based on the charge and a reference comparison signal, the selecting circuit is configured to select, according to a level of the first comparison result signal, a ramp signal among the plurality of ramp signals, and to output the selected ramp signal to the comparing circuit, the comparing circuit includes a first input node for inputting a reset signal and the signal based on the charge, and a second input node for inputting the reference comparison signal and the selected ramp signal, the comparing circuit is configured to generate a second comparison result signal as a result of performing a reset signal comparison of comparing the reset signal with a ramp signal having a first time-changing rate out of the plurality of ramp signals, in a case that the signal based on the charge is smaller than the reference comparison signal, and in a case that the signal based on the charge is larger than the reference comparison signal, the comparing circuit is configured to generate a third comparison result signal as a result of performing a photoelectric conversion signal comparison of comparing the signal based on the charge with the selected ramp signal having a second time-changing rate, which is larger than the first time-changing rate, in a case that the first comparison result signal indicates that the signal based on the charge is larger than the reference comparison signal, or comparing the signal based on the charge with the selected ramp signal having the first time-changing rate in a case that the first comparison result signal indicates that the signal based on the charge is smaller than the reference comparison signal, and the AD converting unit is configured to generate the digital signal based on the reset signal by using the count signal during changing of a level of the second comparison result signal, and to generate the digital signal based on the charge by using the count signal during changing of a level of the third comparison result signal. a photoelectric conversion unit configured to generate a charge based on photoelectric conversion; and an AD converting unit configured to generate a digital signal, including a comparing circuit; a counter circuit configured to generate a count signal by performing a counting operation; a ramp signal generating circuit configured to output a plurality of ramp signals; and a selecting circuit, characterized in that the comparing circuit is configured to generate a first comparison result signal by performing a reference comparison between a signal based on the charge and a reference comparison signal, the selecting circuit is configured to select, according to a level of the first comparison result signal, a ramp signal among the plurality of ramp signals, and to output the selected ramp signal to the comparing circuit, the comparing circuit includes a first input node for inputting a reset signal and the signal based on the charge, and a second input node for inputting the reference comparison signal and the selected ramp signal, the comparing circuit is configured to generate a second comparison result signal as a result of performing a reset signal comparison of comparing the reset signal with a ramp signal having a first time-changing rate out of the plurality of ramp signals, in a case that the signal based on the charge is smaller than the reference comparison signal, and in a case that the signal based on the charge is larger than the reference comparison signal, the comparing circuit is configured to generate a third comparison result signal as a result of performing a photoelectric conversion signal comparison of comparing the signal based on the charge with the selected ramp signal having a second time-changing rate, which is larger than the first time-changing rate, in a case that the first comparison result signal indicates that the signal based on the charge is larger than the reference comparison signal, or comparing the signal based on the charge with the selected ramp signal having the first time-changing rate in a case that the first comparison result signal indicates that the signal based on the charge is smaller than the reference comparison signal, and the AD converting unit is configured to generate the digital signal based on the reset signal by using the count signal during changing of a level of the second comparison result signal, and to generate the digital signal based on the charge by using the count signal during changing of a level of the third comparison result signal.