The present invention provides a communication error detection apparatus that can detect errors of communication networks in a short term after the communication error detection apparatus are installed on the communication networks. In addition, the present invention provides a communication error detection apparatus that can immediately and correctly detect errors occurred in communication networks even if a connection configuration of the communication networks is changed. When the communication error detection apparatus according to the present invention is initially installed, the communication error detection apparatus performs a detection processing of the errors on the basis of a sampling method in which a sampling interval of packet signals up to a start of detection processing is a comparatively short. If the amount of the packet signals, which are sampled and accumulated, reaches a predetermined value, the communication error detection apparatus performs a detection processing of the errors on the basis of another sampling method. In addition, if the detection processing of the errors is temporally released, the another sampling method is changed into a sampling method in which a sampling interval of packet signals up to a start of detection processing is a comparatively short.