Ranging device and driving method of ranging device

A ranging device comprising:

• a light receiving unit configured to generate a signal based on incident light to each of a plurality of photoelectric conversion elements;
• a time counting unit configured to perform time counting;
• a control unit configured to control a light emission timing of a light emitting device that periodically emits light and a timing at which the time counting unit starts time counting;
• a processing unit configured to operate in a first mode for outputting a signal based on incident light to a first number of photoelectric conversion elements among the plurality of photoelectric conversion elements and configured to operate in a second mode for outputting a signal based on incident light to a second number of photoelectric conversion elements among the plurality of photoelectric conversion elements, the second number being different from the first number;
• and
• a time conversion unit configured to generate a signal indicating a time at which light is incident on the light receiving unit based on a time count value input from the time counting unit and a signal generated in the light receiving unit,
• wherein switching from the first mode to the second mode is performed in a period from the start of light emission of the light emitting device to the next start of light emission of the light emitting device.