This paper examines the impact of retail e-commerce on pricing behavior and welfare. Using Japanese data, we find that e-commerce lowered relative inflation rates for goods sold intensively online. We use long time series and historical catalog sales as an instrument for e-commerce sales intensity. The entry of e-commerce firms raised the rate of intercity price convergence in physical stores for goods sold intensively online, but not for other goods, which suggests e-commerce enhances price arbitrage. We estimate that e-commerce lowered variety-adjusted prices on average by 0.9 percent between 1996 and 2014, and more in cities with highly educated populations.