Collation information (22) of data (21) is acquired via a high-secure network (3). The data (21) is acquired via a low-secure network (4). The acquired collation information (22) and data (21) are collated. If the collation result is “match”, it is determined that the low-secure network (4) is not disguised, and access to the low-secure network (4) is permitted. The use of the downloaded data (21) on the high-secure network (3) and low-secure network (4) is permitted.