To provide a method for retaining stocks capable of preventing delay in delivery even if products requiring reproduction arise, while also preventing retention of wasteful stocks that are unlikely to be utilized, and preventing an increase in the burden of stock management business.

The method for retaining stocks for a production process by which a plurality of kinds of products are produced according to customers' orders includes a frequently reproduced kind selecting step for selecting the kinds of products which are frequently reproduced, and a kind-in-stock selecting step by which such kinds of products as each having a distribution of order occurrences and a distribution of reproduction occurrences within a predetermined period both evenly distributed within the predetermined period, are selected as the kinds for stock retention.