This research is a study of a case where the process innovation of small and medium-sized restaurants located in tourist spots is realized by introducing a visitor number prediction formula using big data and improving customer management. With reference to the value chain framework shown in M.E. Porter, the author edited and created a value chain model for small and medium-sized restaurants located in tourist areas. This study focused on triggering innovation in customer management as part of support activities in the value chain. In the example, by utilizing the customer information accumulated in the POS cash register and big data such as the weather and the number of nights, the number of visitors is predicted with an accuracy close to 90%, thereby eliminating the loss of purchase and managing labor and personnel. The result was that the efficiency was improved, and the treatment of employees was improved.