To provide a hydrostatic bulging method capable of easily injecting a pressed fluid between blank mating surfaces without any leakage, a die therefor, a formed article, and a bulging method capable of improving the dent resistance.

In the hydrostatic bulging method in which two overlapped metal plate stocks 5 are pressed and held between a pair of upper and lower dies 10 and 11, the fluid is injected between the mating surfaces of the metal plate stocks, and the metal plate stocks are bulged in a space between die holes 10b and 11b by the pressure, a die injection hole 11d which is communicated with one die holding surface to inject the fluid is formed, a stock injecting through hole which is provided on the die holding surfaces 10a and 10b of the metal plate stock to inject the fluid is aligned to the die injection hole, and the pressed fluid is injected between the mating surfaces of the metal plate stock from the die injection hole through the stock injecting through hole to bulge the metal plate stock.