The surface activated bonding (SAB) technique enables room temperature bonding of metals, such as Au, by forming metal bonds between clean and reactive surfaces. However, the re-adsorption on the activated surface deteriorates the bonding quality, which limits the applicability of SAB for actual packaging processes of electronics. In this study, we propose and demonstrate the prolongation of the surface activation effect for room temperature bonding of Au by utilizing a self-assembled monolayer (SAM) protection. While the bonding without SAM fails after exposure of the activated Au surface to ambient air, the room temperature bonding is achieved using SAM protection even after 100 h exposure. The surface analysis reveals that the clean and activated Au surface is protected from re-adsorption by SAM. This technique will provide an approach of time-independent bonding of Au at room temperature.