Provided is a security box including: an input means for input of external data; an execution means for executing, in a predetermined area, external data input by the input means; and an isolation control means for isolating the execution area from other areas during execution. The security box can be further equipped with: a display means for displaying the behavior of external data executed by the execution means; a determination means for determining, on the basis of the behavior displayed by the display means, whether the external data is normal data; and a deletion means for deleting data that the determination mean has determined is not normal data and/or all of the data of the execution means.