A management system includes a first management device (110) and a second management device (120). The first management device (110) includes a first updater (111) that updates first secret information that is managed in association with a first identifier; a first extractor (112) that extracts a first old fragment and a first new fragment, the first old fragment being included in the first secret information prior to an update but not included in the first secret information subsequent to the update, the first new fragment being not included in the first secret information prior to the update but included in the first secret information subsequent to the update; and a first sender (113) that sends a first notice that specifies the first identifier, the first old fragment, and the first new fragment to the second management device (120). The second management device (120) includes a second receiver (124) that receives the first notice; and a second warning issuer (125) that warns a user using the first identifier to correct second secret information managed in association with the first identifier when the second secret information includes the first old fragment specified in the first notice but does not include the first new fragment specified in the first notice.