We report the distances of molecular clouds at high Galactic latitudes (|b| > 10°) derived from parallax and G-band extinction (A_G) measurements in the second Gaia data release, Gaia DR2. Aided by Bayesian analyses, we determined distances by identifying the breakpoint in the extinction A_G toward molecular clouds and using the extinction A_G of Gaia stars around molecular clouds to confirm the breakpoint. We used nearby star-forming regions, such as Orion, Taurus, Cepheus, and Perseus, whose distances are well known to examine the reliability of our method. By comparing with previous results, we found that the molecular cloud distances derived from this method are reliable. The systematic error in the distances is approximately 5%. In total, 52 molecular clouds have well-determined distances, most of which are at high Galactic latitudes, and we provide reliable distances for 13 molecular clouds for the first time.