This hot-rolled copper alloy sheet contains Mg: 0.2 mass % or more and 2.1 mass % or less, Al: 0.4 mass % or more and 5.7 mass % or less, and Ag: 0.01 mass % or less, with a remainder being Cu and inevitable impurities, an area ratio of Cube orientation (area ratio of crystal orientation) measured by an EBSD method is 5% or less, an average KAM value when a boundary between adjacent pixels where an orientation difference between the pixels is 5° or more is regarded as a crystal grain boundary is 2.0 or less, and an average crystal grain size μ in a sheet-thickness central portion is 40 μm or less.