Optical touch panel and vending machine

The purpose of the present invention is to provide an optical touch panel which, if saturation or reduction in the amount of reflection occurs in detection images, can prevent the deterioration of accuracy of touch detection based on detection images by automatically adjusting to obtain detection images that have a suitable amount of reflection, or by automatically adjusting optical axis misalignment of the optical system that captures detection images; a further purpose of the present invention is to provide a vending machine. To this end, this optical touch panel is provided, for example, with: retroreflective plates 22a, 22b, 22c; an upper left detection unit 23a and an upper right detection unit 23b; a lower left detection unit 23c; a lower right detection unit 23d; an operation determination unit 1; and an exposure time automatic adjustment unit 3 which, if a point with a saturated amount of reflection is detected on the optical axis line of detection images continuously over a set period of time, shortens the exposure time of the detection unit which receives the reflected light, and which, if a point with a reflection amount less than or equal to a threshold value is detected on the aforementioned optical axis line continuously over a prescribed period of time, extends the exposure time of the detection unit which receives the reflected light.