The test result of a double-sided silicon strip detector (DSSD) obtained using a 45-MeV proton beam from the MC-50 cyclotron at Korea Institute of Radiological and Medical Science (KIRAMS) in Seoul, Korea, is presented. The manufactured DSSD consists of the double-sided silicon strip sensor and front-end electronics for signal readout. The implanted strips on the p-side are perpendicular to those on the n-side to provide two dimensional position information. The strip sensor has 512 readout channels on each side, and its size is 5.56 cm $ imes$ 2.95 cm. For the sensor signal readout, we use a VA1TA-3 ASIC chip from Gamma Medica-Ideas, Norway, which provides analog outputs of 128 channels and a wire-OR'ed trigger output for every event. We present the details of the readout electronics systems and the beam test result of the sensor-electronics assembly.