We have developed an all-polymer built-in micropump driven by light using viscous drag exerted on a microrotor. The micropump consists of a helical rotor and a U-shaped microchannel. The rotor can be driven just by focusing a laser beam without a laser scanning system. The optical torque exerted on the rotor was analyzed by Finite Difference Time Domain (FDTD) method. The flow field inside the microchannel was also analyzed by Finite Elemental Method (FEM) based on the Navier-Stokes equation to optimize the channel shape. A prototype of the micropump was fabricated by using two-photon microstereolithography. It was demonstrated that the rotation of the helical rotor generated fluid flow. The optically driven micropump using the helical rotors will be useful for lab-on-a-chip devices.