Bubble generating device and bubble generating system

A bubble generating device attachable to a liquid tank and operable to generate fine bubbles in a liquid in the liquid tank, the bubble generating device comprising:

• a vibration plate including a plurality of openings and at a position at which a first surface of the vibration plate is in contact with the liquid in the liquid tank and at which a second surface of the vibration plate is in contact with a gas;
• a first cylindrical body that includes a first end portion supporting the vibration plate;
• a spring portion that has a plate shape and that supports a second end portion of the first cylindrical body;
• a second cylindrical body that includes a first end portion supporting the spring portion at a position outward of a position at which the first cylindrical body is supported;
• and
• a piezoelectric element to cause the spring portion to vibrate;
• wherein
• the piezoelectric element is positioned inward of a portion of a surface of the spring portion supported by the second cylindrical body.