We report the coherent resonant emission of the exciton state in a single InAs quantum dot,embedded in a 0planar optical microcavity.The quantum dot is excited by a laser beam from the cleaved sample edge,and the resonant fluorescence is collected in the direction perpendicular to the excitation laser beam,so the residual laser scattering can be deeply suppressed.This experimental setup enables us to observe Rabi oscillation and a Mollow triplet with Rabi energy up to about 27μeV.