Provided is a photoelectric sensor capable of enhancing display flexibility of a display section mounted on the photoelectric sensor and making this display flexibility contribute to improvement in user's operability. In a Run mode, a current value is displayed in large-sized numerals on a display section. When switching is made from the Run mode to a setting mode and letter information is to be displayed in the setting mode, a current value is displayed in relatively small-sized numerals at the corner (e.g., lower left) of the display section.