To provide a materials monitoring method and device of a high-rise warehouse capable of knowing the attitude of each piece of materials on a lifter arm of its crane to transport the materials and securing the safety of the operations.

A judging means 117 confirms how long each piece of materials W is to be measured by a length measuring sensor 71 and whether the material W is not ranging out of the lifter arm 55 to be informed by material rangeout sensors 61 and 63, judges that the material W is not ranging out over the region stored in a memory 115 previously, and performs transportation if not. In the case the lifter arm 55 is used in the form capable of being put out and set in, the output operation for transportation is conducted upon confirming by lifter arm sensors 65 and 67 that the lifter arm 55 is set in the specified position. Even in the case the material W ranges out over the rangeout region, the judging means 117 does not make a rangeout sensing so that particular pieces of operations can be done as long as it concerns the input/discharge area and material replacement area.