I document trends of concentration in national and local markets in Japan since 1980. First, national market concentration within industries or product categories has increased since the mid-1990s regardless of sectors, data sources, and measurements. This is consistent with the findings in other developed countries, including the US. Second, local market concentration has also increased since the late 1990s, which contrasts with the findings in the US that the local market concentration has been decreasing recently. The increase in local market concentration is associated with the decline in the number of establishments and is concentrated in the areas outside large cities.