Provided is a missing step detection device which can be miniaturized even when the clearance between adjacent steps is wide. The missing step detection device has a plurality of steps which are connected together in an endless manner and perform circulating movement, a first proximity sensor which is provided outside the steps in the vicinity of the steps and detects step surfaces of the steps which are approaching, a second proximity sensor which is provided in the vicinity of the steps so as to detect portions of the steps which are approaching, and detects portions of the steps which are different from the steps whose step surfaces are detected by the first proximity sensor for a shorter time than the time during which the first proximity sensor is detecting the step surfaces, and a judgment device which judges that there is no missing condition of the steps when the first proximity sensor detects the step surfaces during the detection of portions of the steps by the second proximity sensor, and judges that there is a missing condition of the steps when the first proximity sensor does not detect the step surfaces.