To provide a customer management device, program and method capable of effectively sending direct mails.

A customer management device includes: a determination unit for determining whether or not there is the possibility that goods to be exhibited in a scheduled event are sold out during an event holding period, based on a purchase detail TB (Steps S12 and S14); a determination unit for, when there is the possibility of a sold-out as the result of the determination, determining an index value (DM response) of a visiting period of customers during the event, based on DM effect information TB (Step S20); and an extraction unit for extracting customers to which direct mails are sent, based on the index value (DM response) of the visiting period (Step S22).