San Juan is a district of the Naranjo canton, in the Alajuela province of Costa Rica.
San Juan was created on 31 March 1966 by Decreto Ejecutivo 11. Segregated from Naranjo.
San Juan has an area of km<sup>2</sup> and an elevation of metres.
For the 2011 census, San Juan had a population of inhabitants.
The district is covered by the following road routes: