To provide a liquid concentration detection apparatus capable of detecting a concentration of a specific component in a liquid and a liquid level by the same detection part.

When a fuel temperature T detected by a thermistor 19 attached to a warning detection electrode 15 is a temperature indicating that a fuel is reduced lower than a warning liquid level, a CPU 32 turns on a warning lamp 42 to perform residual quantity warning (S5). The CPU 32 detects reference capacity Cε by an exposure detection electrode 15a formed on the tip side of the warning detection electrode 15 (S6) and calculates an ethanol concentration E on the basis of the temperature T and the reference capacity Cε (S8). The CPU 32 detects electrostatic capacity C_A by a liquid level detection electrode 9, calculates a liquid level L by using the reference capacity Cε (S10) and instructs an indicator 41c in a meter 40 to indicate the liquid level (S11).