A fan-in/out polymer optical waveguide with 25-μm cores and 40-μm interchannel pitch is fabricated for a multimode multicore fiber using a microdispenser. We design a fan-in/out structure to which the Mosquito method is applicable since the Mosquito method is capable of drawing a circular graded-index core three-dimensionally. Then, we experimentally fabricate a 10-cm long fan-in/out polymer waveguide with seven cores, which is expected to connect a multicore fiber and a fiber ribbon. A minimum insertion loss of 5.26 dB at 850-nm wavelength for a 10-cm long fan-in/out waveguide is experimentally observed. Causes of variation in the insertion loss and interchannel pitch are discussed.