Tokyo ETS is the first emissions trading scheme to control GHG emissions from office buildings. Although the Tokyo government claimed that Tokyo ETS had been successful, some argued that the emission reduction under Tokyo ETS was actually the result of electricity price increases triggered by the Great East Japan Earthquake in 2011. Using a facility-level data set for Japanese office buildings, we conducted an econometric analysis to examine the impact of Tokyo ETS. We found that half of the emission reduction is a result of the ETS, while the rest of the reduction is due to the electricity price increase. Another unique feature of Tokyo ETS is that an accurate permit price is not publicly available due to its design. Using our estimated model, we found that the price is approximately $50 per ton of CO 2 in the early phase.