A ferritic stainless steel sheet for a water heater comprising, in terms of mass %, 0.020% or less of C, 0.30 to 1.00% of Si, 1.00% or less of Mn, 0.040% or less of P, 0.010% or less of S, 20.0 to 28.0% of Cr, 0.6% or less of Ni, 0.03 to 0.15% of Al, 0.020% or less of N, 0.0020 to 0.0150% of 0, 0.3 to 1.5% of Mo, 0.25 to 0.60% of Nb, and 0.05% or less of Ti, the remainder being composed of Fe and unavoidable impurities, and the ferritic stainless steel sheet satisfying the following formulae (1) and (2):
- 25≦Cr+3.3 Mo≦30 (1)
- 0.35≦Si+Al≦0.85 (2)
- wherein Cr, Mo, Si, and Al represent the contents (mass %) of Cr, Mo, Si, and Al, respectively.