A time-slice global warming experiment was performed with a very high-resolution (20-km mesh) atmospheric general circulation model. Due to increased horizontal resolution, land-sea distribution over the Indonesian Maritime Continent is well represented. A clear contrast in precipitation change at the end of the twenty-first century is found over Borneo Island and the Java Sea: over the ocean morning precipitation decreases and evening precipitation increases, while over the island morning precipitation increases, resulting in reduced amplitude of rainfall diurnal variation over both land and ocean. Weakened land-sea breeze circulation by global warming due to larger nighttime temperature increases over land than during the day contributes to this decreased rainfall diurnal variation.