By registering a set range and a sound type which are not subject to detection of an abnormal sound in advance, a PC performs an alert notification in a case of detecting a sound which is regarded as an abnormal sound, and does not perform an alert notification in a case of detecting a sound which is not regarded as an abnormal sound. That is, in a target area such as a hotel lobby, a sound output from a television provided therein, a water sound emitted by a fountain, and the like are no longer erroneously detected as an abnormal sound. Further, the PC forms the directivity of sound data in a direction toward an actual position corresponding to a designated position on an image of a sound pickup area displayed on a display.