There is provided a solid state image sensor including a photoelectric conversion unit formed and embedded in a semiconductor substrate, an impurity region that retains an electric charge generated by the photoelectric conversion unit, and a transfer transistor that transfers the electric charge to the impurity region. A gate electrode of the transfer transistor is formed in a depth direction toward the photoelectric conversion unit in the semiconductor substrate, from a surface of the semiconductor substrate on which the impurity region is formed. A channel portion of the transfer transistor is surrounded by the gate electrode in two or more directions other than a direction of the impurity region, as seen from the depth direction.