Supply liquid tank unit and ink jet recording apparatus including the same

The supply liquid tank unit of the disclosure includes a supply liquid tank, and a detection sensor. The detection sensor detects a liquid level of liquid in the supply liquid tank. The supply liquid tank includes a first chamber provided with an inflow port, a second chamber provided with an outflow port, a partition wall for partitioning the first chamber and the second chamber from each other, and a lower communicating path which is formed from a lower end of the partition wall and a lower surface of the supply liquid tank and which makes the first chamber and the second chamber communicating with each other. The detection sensor detects a liquid level of the liquid in the second chamber and is placed above the lower end of the partition wall.