This invention has been realized in order to obtain green compacts of a fixed height by pressure molding of material powder with a fixed gap between upper and lower punches. A powder compacting method of this invention performs a punch driving step wherein, after filling material powder in a cavity, the material powder filled in the cavity is pressure molded by using an upper punch and a lower punch, said punch driving step comprising a primary driving step of driving either one of the punches until the thickness of the cavity formed between the upper and lower punches becomes slightly greater than a target molding thickness, and a secondary driving step of measuring a gap between the upper and lower punches and driving either one of the punches while controlling it until the measured value reaches the target molding thickness.