The paper presents the improvements and enhancements made to the Model for Interdisciplinary Research on Climate (MIROC) by the Japanese research community. The new version, MIROC5, is compared with the previous version, MIROC3.2, in terms of mean states and variability. MIROC5 shows significant improvements in precipitation, zonal mean atmospheric fields, equatorial ocean subsurface fields, and El Niño-Southern Oscillation (ENSO) simulation. The differences between MIROC5 and MIROC3.2 are larger than those between the two MIROC3.2 versions with different resolutions, indicating that updating parameterization schemes has a greater impact on model climate than increasing resolution. The mean cloud properties in MIROC5 agree well with satellite measurements, and the model reveals an equilibrium climate sensitivity of 2.6 K, lower than the 3.6 K in MIROC3.2. This sensitivity is attributed to the negative feedback of low clouds on increasing CO₂ concentrations. The paper also discusses the model's performance in various climatological fields, including sea surface temperature, sea surface salinity, precipitation, zonal winds, and ocean subsurface states, highlighting the improvements and remaining biases.The paper presents the improvements and enhancements made to the Model for Interdisciplinary Research on Climate (MIROC) by the Japanese research community. The new version, MIROC5, is compared with the previous version, MIROC3.2, in terms of mean states and variability. MIROC5 shows significant improvements in precipitation, zonal mean atmospheric fields, equatorial ocean subsurface fields, and El Niño-Southern Oscillation (ENSO) simulation. The differences between MIROC5 and MIROC3.2 are larger than those between the two MIROC3.2 versions with different resolutions, indicating that updating parameterization schemes has a greater impact on model climate than increasing resolution. The mean cloud properties in MIROC5 agree well with satellite measurements, and the model reveals an equilibrium climate sensitivity of 2.6 K, lower than the 3.6 K in MIROC3.2. This sensitivity is attributed to the negative feedback of low clouds on increasing CO₂ concentrations. The paper also discusses the model's performance in various climatological fields, including sea surface temperature, sea surface salinity, precipitation, zonal winds, and ocean subsurface states, highlighting the improvements and remaining biases.