We report the observation of a fractional topological magneto-electric effect in Sr2RuO4 single crystal thin films by measuring the electric transport properties. In the absence of an external magnetic held, the surface transport in Sr2RuO4 thin films exhibited a fractional quantum Hall conductance in the superconducting state. The fractional magnetic-held-induced electric polarization was observed under zero bias current. We can understand the fractional quantum Hall conductance as a consequence of the observation of the (2 + 1)-dimensional topological surface state in the (3 + 1)-dimensional fractional topological magneto-electric effect in Sr2RuO4 thin films. (C) 2014 Elsevier B.V. All rights reserved.