We present a measurement of the cosmic microwave background lensing potential using 500 deg 2 of 150 GHz data from the SPTpol receiver on the South Pole Telescope. The lensing potential is reconstructed with signal-to-noise per mode greater than unity at lensing multipoles L≲ 250, using a quadratic estimator on a combination of cosmic microwave background temperature and polarization maps. We report measurements of the lensing potential power spectrum in the multipole range of 100< L< 2000 from sets of temperature-only (T), polarization-only (POL), and minimum-variance (MV) estimators. We measure the lensing amplitude by taking the ratio of the measured spectrum to the expected spectrum from the best-fit Λ cold dark matter model to the Planck 2015 TT+ low P+ lensing data set. For the minimum-variance estimator, we find ${A} _ {\mathrm {MV}}= 0.944\pm 0.058 (\mathrm {Stat}.)\pm 0.025\(\mathrm {Sys}.); $