PURPOSE: To avoid a fact that sufficient information cannot be obtained because information of a line is effected by information of other line by collecting information of each line to other area for each line.

CONSTITUTION: Information collection storage areas 21, 22,..., 2N are respectively related to lines 31, 32,..., 3N. A trace information collection recording tool 1 collects information to be communicated according to various transmission processing procedures sequentially in the lines 31, 32,..., 3N. In the case of collecting information, a line identification data stored in part of the information is referenced to identify on which line the information is communicated. When it is identified that the relevant line is a line 3N based on the referenced data, the collected information is stored in the information collection storage area 2N made corresponded to the line 3N and the processing is restored to the processing to collect succeeding information.