1. An image processor, comprising: an image pickup part configured to pick up a pickup image of a certain area; an irradiator configured to irradiate at least a part of the certain area for the pickup image picked up by the image pickup part; an extractor configured to extract, as an irradiation image, a light irradiated from the irradiator, the irradiation image being extracted from the pickup image picked up by the image pickup part; an image generating part configured to generate an irradiation removed image which is obtained by removing the irradiation image from the pickup image; an object recognizer configured to recognize an object in the certain area, based on the irradiation removed image generated by the image generating part; a distance sensor configured to sense a distance to the object recognized by the object recognizer; and an administrative processor configured to administratively control each of the image pickup part, the irradiator, the extractor, the image generating part, the object recognizer, and the distance sensor, the administrative processor including: a frequency analyzer configured to analyze a frequency component of a signal of an original image which is the pickup image including an external light and obtained by the image pickup part, and a controller configured to: control the irradiator such that the irradiator is set to have an irradiation period different from a period of the frequency component of the external light obtained by the frequency analyzer, and control the extractor to be in conformity with the irradiation period of the irradiator.