The present invention provides an ear thermometer that irradiates liquid crystal with backlight without increasing a battery capacity, to make a body temperature displayed with the liquid crystal easily visible even in a dark place. An MCU 1 displays a body temperature measured by a body temperature measuring part (3) on a liquid crystal display part (5), controls, through input/output ports (P1, P2), a backlight emitting part (7) in such a way that the light quantity of the backlight irradiating the liquid crystal display part (5) from the backlight emitting part (7) is maximized for a first predetermined time, controls the backlight emitting part (7) in such a way that the quantity of the backlight keeps, for a second predetermined time that follows the first predetermined time, a predetermined level that is lower than the maximum, and controls the backlight emitting part (7) in such a way that the quantity of the backlight is zeroed after the second predetermined time elapses.