The present technology relates to a comparator circuit, a solid-state imaging apparatus, and an electronic device which enable to improve a frame rate. A comparator compares an analog signal with a reference signal, an amplification stage amplifies output of a comparing unit and has different output change speeds in normal rotation and in reverse rotation, and a switch circuit fixes an input node or an output node of the amplification stage to a predetermined voltage in a predetermined period before a comparing operation by the comparator so that the amplification stage operates in a change direction having a higher output change speed. The present technology can be applied to a comparator circuit provided to an A/D converter of a CMOS image sensor.