PROBLEM TO BE SOLVED: To provide a solid composition showing excellent foaming in a stomach and having a good flavor.SOLUTION: A solid composition has following components (A), (B) and (C): (A) plant-derived protein and/or peptide with an insoluble component amount of 25 mass% or more, (B) carbonate 5-30 mass%, and (C) organic acid 5-30 mass%, with an equivalent ratio between component (C) and component (B) [(C) equivalent/(B) equivalent] of 0.4-4.SELECTED DRAWING: None