In the image capturing apparatus M, the optical path difference producing member 21 is disposed on the second optical path L2. Thereby, it is possible to suppress the amount of light when an optical image which is focused at the front of an optical image made incident into the first imaging device 18 (front focus) and an optical image which is focused at the rear thereof (rear focus) are respectively imaged at the second imaging device 20 and also to secure the amount of light on image pickup by the first imaging device 18. Further, in the image capturing apparatus M, a position of the first imaging region 22A and a position of the second imaging region 22B on the imaging area 20a are reversed with respect to the axis P in association with reversal of a scanning direction of the sample S. Therefore, despite the scanning direction of the sample S, it is possible to obtain a deviation direction of the focus position under the same conditions.