A system for preventing illegitimate outflow of an electronic document, the system comprising: a first and a second taking-out control unit (40, 80), each configured to generate a virtual disk (30, 70) which is a space for storing an electronic document to be controlled and to control taking-out of the electronic document; a taking-out management server unit configured to authenticate whether the taking-out of the electronic document is legitimate taking-out; and a self-response agent unit configured to perform self-extinction when a result indicating illegitimate outflow is received from the taking-out management server unit, wherein: the first taking-out control unit is included in a personal computer unit of a taking-out approval requester and the second taking-out control unit is included in a PC unit of a taking-out approval granter; and the first taking-out control unit of the PC unit of the taking-out approval requester is configured to generate a taking-out request draft of the electronic document and to send the taking-out request draft to the PC unit of the taking-out approval granter via the taking-out management server unit, the second taking-out control unit of the PC unit of the taking-out approval granter is configured to approve the taking-out of the electronic document and to send a result of the approval to the first taking-out control unit of the PC unit of the taking-out approval requester via the taking-out management server unit in response to receiving a taking-out request draft; wherein the first taking-out control unit of the PC unit of the taking-out approval requester is configured to send the self-response agent unit to a target to which the electronic document is to be transferred; and wherein the self-response agent unit provides the taking-out management server unit with information about a target to which the electronic document is to be transferred in order to request authentication from the taking-out management server unit. a first and a second taking-out control unit (40, 80), each configured to generate a virtual disk (30, 70) which is a space for storing an electronic document to be controlled and to control taking-out of the electronic document; a taking-out management server unit configured to authenticate whether the taking-out of the electronic document is legitimate taking-out; and a self-response agent unit configured to perform self-extinction when a result indicating illegitimate outflow is received from the taking-out management server unit, wherein: the first taking-out control unit is included in a personal computer unit of a taking-out approval requester and the second taking-out control unit is included in a PC unit of a taking-out approval granter; and the first taking-out control unit of the PC unit of the taking-out approval requester is configured to generate a taking-out request draft of the electronic document and to send the taking-out request draft to the PC unit of the taking-out approval granter via the taking-out management server unit, the second taking-out control unit of the PC unit of the taking-out approval granter is configured to approve the taking-out of the electronic document and to send a result of the approval to the first taking-out control unit of the PC unit of the taking-out approval requester via the taking-out management server unit in response to receiving a taking-out request draft; wherein the first taking-out control unit of the PC unit of the taking-out approval requester is configured to send the self-response agent unit to a target to which the electronic document is to be transferred; and wherein the self-response agent unit provides the taking-out management server unit with information about a target to which the electronic document is to be transferred in order to request authentication from the taking-out management server unit. the first taking-out control unit is included in a personal computer unit of a taking-out approval requester and the second taking-out control unit is included in a PC unit of a taking-out approval granter; and the first taking-out control unit of the PC unit of the taking-out approval requester is configured to generate a taking-out request draft of the electronic document and to send the taking-out request draft to the PC unit of the taking-out approval granter via the taking-out management server unit, the second taking-out control unit of the PC unit of the taking-out approval granter is configured to approve the taking-out of the electronic document and to send a result of the approval to the first taking-out control unit of the PC unit of the taking-out approval requester via the taking-out management server unit in response to receiving a taking-out request draft; wherein the first taking-out control unit of the PC unit of the taking-out approval requester is configured to send the self-response agent unit to a target to which the electronic document is to be transferred; and wherein the self-response agent unit provides the taking-out management server unit with information about a target to which the electronic document is to be transferred in order to request authentication from the taking-out management server unit.