An oil degradation meter and a method for evaluating oil degradation are provided, in which a user is enabled to arbitrarily set a degradation of oil/fat using an acid value (AV value) as an index, and capable of learning a replacement time of oil/fat easily with a stable reproducibility, even in a case where a condition such as a moisture amount in food (deep-fried food) is different. In a setup procedure, an acid value (AV0) of unused oil/fat is set to 0, a dielectric constant (D0) at that time is measured and recorded, a dielectric constant (D100) of oil/fat at a replacement time under a specific oil/fat usage condition is measured, and it is recorded along with an acid value (AV100) at that time, and in a measurement procedure, a dielectric constant (Dn) of the sample oil/fat is measured, and an acid value (AVn) of said sample oil/fat is calculated based on the dielectric constants (D0, D100) and the acid value (AV100) recorded in said setup procedure, according to a calculation formula of [AVn=AV100×{(Dn−D0)/(D100−D0)}].