The present invention provides an electro-optical distance measurement, wherein a light from a light source (6) is projected toward an object to be measured (2), a reflection light reflected by the object to be measured is received at a photodetection unit (8), the light from the light source is received by the photodetection unit as an inner light via an inner optical path (11), and a distance to the object to be measured is measured according to the result of photodetection of the reflection light and the inner light of the photodetection unit, and wherein a correction information is acquired based on the inner light, the acquired correction information is stored, a correction value is obtained from the correction information based on the reflection light and the inner light, and a distance is calculated from the correction value and the result of photodetection of the reflection light and the inner light.