The structure of the SrTiO3/Si interface is determined by high-angle annular dark field imaging in combination with a recently developed technique based on aberration-corrected high-resolution transmission electron microscopy. At the interface, a monolayer of SrO faces the terminating plane of silicon. In this monolayer, the strontium atoms lie above the face-center of four silicon atoms in the terminating plane, and the oxygen atoms are located directly above the terminating silicon atoms. This structure, which is the dominant type of interface structure observed in this system, agrees with one of the interface structures predicted by first-principles calculations.