The role of the botanical garden in securing biodiversity, responding to climate change, and sustainable development in modern cities is becoming more important. Private botanical gardens that lead the domestic botanical culture are declining due to complex reasons such as an increase of tourist destinations, lack of policy support, lack of introduction of advanced management strategies, and similar leisure activities to national and public botanical gardens. The Private Botanical Garden not only has a large number of plant species with high conservation value, but also provides various public utilities as a cultural and educational space and government efforts are needed to activate the operation of this amenity. The purpose of this study is to evaluate the value of public functions provided by private botanical gardens using the Contingent Valuation Method (CVM). In this way, the government aims to provide a basis for policy and institutional support for private botanical gardens. The main results are as follows. First, public utility functions provided by private botanical gardens were recognized as ‘preservation’ (23.4%), ‘recreation and tourism’ (17.5%) and ‘research’ (16.6%) in order of analytic hierarchy process (AHP). Second, ‘heritage value’ (33.0%) and ‘existence value’ (32.5%) were recognized as significant among the values provided by private botanical gardens. Third, the willingness to pay (WTP) to preserve the public functions of the private botanical garden was 12,234 won. Based on this, the economic value of all private botanical gardens in the whole country was estimated, resulting in about 233.8 billion won. There is a need to revise laws and regulations related to financial support for the revitalization and quality improvement of private botanical gardens. It is also necessary to establish a cooperative operating system between national, public and private botanical gardens.