To provide a correction method for a liquid level detection device and the liquid level detection device, capable of performing high-accuracy liquid level detection, by correcting the measured electrostatic capacity and obtaining corresponding detection value.

A reference displacement straight line (A), indicating the displacement relation between the level of urea solution and an electrostatic capacity is calculated beforehand, by using a reference sensor portion. In a liquid level sensor manufacturing process, the electrostatic capacity C1(l1) of a sensor portion, formed when the level of the urea solution is l1, is measured. Next a displacement straight line (B) of the sensor portion is calculated by the method of least squares, setting the zero value (0, 0) of the electrostatic capacity and a measured value (l1, C0(l1)) as parameters. Then correction values for making the displacement line (B) coincide with the reference line (A) are calculated. By using these correction values and correcting measured electrostatic capacities the completed liquid level sensor performs high-accuracy level detection .