To provide a range finder capable of obtaining highly accurate and correct range finding information, even from a low-contrast subject.

The range finder having a passive range finding means, is provided with a photodetecting sensor 1, a lens driving means 3 and a control means 2 for controlling the whole system, and in the case it is impossible to judge in the whole range finding area, the weight is obtained based on the range finding result from the area where the range finding results are concentrated most, the range finding accuracy estimation value is calculated and an optimum range finding result is obtained.