A distance measuring device comprising: a sensor section configured to convert a reflected light of the laser beam irradiated in a first irradiation direction and a reflected light of the laser beam irradiated in a second irradiation direction via a light receiving optical system to a first time series digital signal and a second time series digital signal, wherein the first time series digital signal and the second time series digital signal are sampled at the same time interval; characterized by further comprising: a weight value generator configured to generate a weight value that increases as a similarity between the first time series digital signal and the second time series digital signal increases; a cumulative signal generator configured to accumulate the first time series digital signal and the second time series digital signal based on the weight value to generate a third series digital signal; and a distance measurer configured to measure a distance to a target object on the basis of a time difference between irradiation timing of the laser light and timing of a peak position in the third series digital signal, wherein the weight value generator is further configured to calculate the similarity based on time series correlation of the first time series digital signal and the second time series digital signal, wherein the similarity increases as the time series correlation increases. a sensor section configured to convert a reflected light of the laser beam irradiated in a first irradiation direction and a reflected light of the laser beam irradiated in a second irradiation direction via a light receiving optical system to a first time series digital signal and a second time series digital signal, wherein the first time series digital signal and the second time series digital signal are sampled at the same time interval; characterized by further comprising: a weight value generator configured to generate a weight value that increases as a similarity between the first time series digital signal and the second time series digital signal increases; a cumulative signal generator configured to accumulate the first time series digital signal and the second time series digital signal based on the weight value to generate a third series digital signal; and a distance measurer configured to measure a distance to a target object on the basis of a time difference between irradiation timing of the laser light and timing of a peak position in the third series digital signal, wherein the weight value generator is further configured to calculate the similarity based on time series correlation of the first time series digital signal and the second time series digital signal, wherein the similarity increases as the time series correlation increases. a weight value generator configured to generate a weight value that increases as a similarity between the first time series digital signal and the second time series digital signal increases; a cumulative signal generator configured to accumulate the first time series digital signal and the second time series digital signal based on the weight value to generate a third series digital signal; and a distance measurer configured to measure a distance to a target object on the basis of a time difference between irradiation timing of the laser light and timing of a peak position in the third series digital signal, wherein the weight value generator is further configured to calculate the similarity based on time series correlation of the first time series digital signal and the second time series digital signal, wherein the similarity increases as the time series correlation increases.