  Thermal convection is commonly believed to be the energy source of stellar or
planetary dynamo. In this short paper we provide another possibility, namely
large-scale tidal flow. In close binary stars, say, solar-like stars with
orbital period at 2 or 3 days, large-scale tidal flow is comparable to or even
stronger than convective flow, and it can induce magnetic dynamo action. Based
on dynamo equation and tidal theory we estimate the magnetic energy induced by
large-scale tidal flow, which is proportional to the cube of orbital frequency.
Our estimation can be tested by the future spectropolarimetric observations and
numerical simulations for close binary stars.
