The present invention relates to an infrared detector element to detect infrared rays by means of a pyroelectric material, and an infrared sensor unit and an infrared detecting device using the infrared detector element and has an object of realizing an omnidirectional infrared detector element that can gain an output against an object to be detected moving in whatever directions. In order to accomplish this object, the present invention proposes a setup comprising a pair of first electrodes (12, 13), which have a function of absorbing infrared rays, are close to trapezoidal in shape, respectively, and are disposed on one of the surfaces of a pyroelectric material (11) with electrical connections made in such a way that the first electrodes are opposite to each other in polarity, and a pair of second electrodes (14, 15) disposed on the other surface of the pyroelectric material (11) and electrically connected with each other, in which the lower side of the close to trapezoidal shape of the first electrodes (12, 13) of one hand is aligned in the same direction as the lower side of the close to trapezoidal shape of the second electrodes (14, 15) of the other hand, thereby producing an effect of gaining an output against an object to be detected making a movement from whatever directions.