Recently, the miniaturization limits of fabrications have approached the order of molecular size. In order to measure the electric characteristics of a single molecule, it is necessary to fabricate not only the molecular-sized nanogap electrodes but also the stable chemical bonds established from a single molecule to two facing electrodes. In this paper, the author demonstrated a procedure for fabricating molecular-sized nanogap electrodes and a steadiness of the bridge-structure depending on molecular structure of bridge-molecules.