Abstract: The shutter construction of a tympanic thermometer comprises a base formed with a horizontal groove and a vertical slot that communicate with each other, wherein said horizontal groove is for mounting a wave guiding duct; a supporting frame formed at the rear end of said base and formed with at least a first engaging portion and at least a second engaging portion; a shutter plate mounted in said vertical slot for closing said wave guiding duct; a linking element, the fore end of the linking element being coupled to the lower portion of said shutter plate and the rear end of the linking element being engaged with said first engaging portion of said supporting frame so that the fore end of the linking element can be swayed up and down relative to the rear end thereof; a spring element, the fore end of the spring element being coupled to said linking element; and an actuating element, the fore end of the actuating element being engaged with said second engaging portion of said supporting frame and the rear end o