A method of manufacturing an electronic component substrate is provided, the method allowing manufacturing yield to be improved. The method of manufacturing an electronic component substrate in which a plurality of electronic components are mounted on a first substrate includes the steps of: aligning and disposing the plurality of electronic components on a second substrate; transferring the electronic components on the second substrate onto the first substrate; detecting an electronic component un-mounted portion on the first substrate; and repairing by selectively re-transferring the electronic component from the second substrate onto the detected un-mounted portion on the first substrate.