In the Korean housing market, mass customization (MC) is an inevitable strategy for ensuring competitiveness. However, though customer needs have varied rapidly under the customer-oriented market conditions, the level of customization for houses has been restricted by economics of scale in the construction processes. With the rise of the level of customization, the cost of site management has increased because of additional labour. Therefore, this paper introduces the finishing information system (FIS), which can be used to minimize the additional commitment of manpower due to higher levels of MC. To illustrate and validate this system, a case study was performed in a real apartment complex project. The results showed that additional manpower for site management was decreased by quicker completion of the job, simplification of the management process, and efficiency of communication.