An information processing device comprising: a processor, wherein the processor is configured to: associate a plurality of participants of each activity set by a user for each specific purpose with the activity; link, to the activity, a storage area of a file management service for which at least one participant has an access right and that is provided by a plurality of service providers; and cause a display of a participant of a request source to display a first file stored in a linked storage area for which the participant of the request source has an access right, in response to a request for accessing the activity from each participant, wherein the processor is further configured to: link, to the activity, a messaging service for which at least one participant has an access right and in which at least a message (M1-M15) is exchanged; and cause the display to display a list of second files (F1-F9) that are transmitted to the linked messaging service for which the participant of the request source has an access right, together with the first file; and in response to a selection of a permission by the participant of the request source, display a third file, for which the participant of the request source has an access right and that is stored in a storage area different from the linked storage area, for another participant which has a certain permission or more; wherein the selection of the permission is from a list of permissions of other participants who are granted with an access right to the third file. a processor, wherein the processor is configured to: associate a plurality of participants of each activity set by a user for each specific purpose with the activity; link, to the activity, a storage area of a file management service for which at least one participant has an access right and that is provided by a plurality of service providers; and cause a display of a participant of a request source to display a first file stored in a linked storage area for which the participant of the request source has an access right, in response to a request for accessing the activity from each participant, wherein the processor is further configured to: link, to the activity, a messaging service for which at least one participant has an access right and in which at least a message (M1-M15) is exchanged; and cause the display to display a list of second files (F1-F9) that are transmitted to the linked messaging service for which the participant of the request source has an access right, together with the first file; and in response to a selection of a permission by the participant of the request source, display a third file, for which the participant of the request source has an access right and that is stored in a storage area different from the linked storage area, for another participant which has a certain permission or more; wherein the selection of the permission is from a list of permissions of other participants who are granted with an access right to the third file. associate a plurality of participants of each activity set by a user for each specific purpose with the activity; link, to the activity, a storage area of a file management service for which at least one participant has an access right and that is provided by a plurality of service providers; and cause a display of a participant of a request source to display a first file stored in a linked storage area for which the participant of the request source has an access right, in response to a request for accessing the activity from each participant, wherein the processor is further configured to: link, to the activity, a messaging service for which at least one participant has an access right and in which at least a message (M1-M15) is exchanged; and cause the display to display a list of second files (F1-F9) that are transmitted to the linked messaging service for which the participant of the request source has an access right, together with the first file; and in response to a selection of a permission by the participant of the request source, display a third file, for which the participant of the request source has an access right and that is stored in a storage area different from the linked storage area, for another participant which has a certain permission or more; wherein the selection of the permission is from a list of permissions of other participants who are granted with an access right to the third file. link, to the activity, a messaging service for which at least one participant has an access right and in which at least a message (M1-M15) is exchanged; and cause the display to display a list of second files (F1-F9) that are transmitted to the linked messaging service for which the participant of the request source has an access right, together with the first file; and in response to a selection of a permission by the participant of the request source, display a third file, for which the participant of the request source has an access right and that is stored in a storage area different from the linked storage area, for another participant which has a certain permission or more; wherein the selection of the permission is from a list of permissions of other participants who are granted with an access right to the third file.