carbonizing waste printed circuit board together with a calcium compound at 400° C. to 600° C. in a non-oxidizing atmosphere to fix a halogen contained in the board as calcium halide and to melt a solder of the board to allow mounted parts to be easily separated from the board;

performing crushing after the carbonizing; and

sieving crushed materials into fine particles of less than 0.5 mm containing the calcium compounds, medium particles containing the mounted parts, and coarse particles containing board pieces such that the crushed materials are sorted into the calcium compounds, the mounted parts, and the board pieces;

wherein

the crushed materials are sieved into the fine particles of less than 0.5 mm containing the calcium compounds, medium particles of 0.5 mm or more and 50 mm or less containing the mounted parts, and coarse particles of more than 50 mm containing the board pieces.