Puzzle, puzzle piece and method for making puzzle

A jigsaw puzzle piece capable of interlocking with other pieces by interlocking portions each composed of at least one pair of projections and recesses and provided on a corresponding one of four sides of a square, wherein:

• the respective sides are formed to be point symmetrical with respect to a center of the square;
• and
• the pieces can interlock with other pieces in four upward, downward, leftward and rightward directions, whereas the respective sides of the piece are shaped such that projection-adjacent-side-portions adjacent to the projections are displaced inwardly of the square and recess-adjacent-side-portions adjacent to the recesses are displaced outwardly of the square with respect to a virtual reference line composed of sides of a square, the projections and the recesses are moved on the virtual reference line by distances corresponding to respective displacements, thereby preventing unevenness on sides of adjacent pieces when the pieces interlock with other pieces, and a maximum width of enlarged portions of the projections is set larger than a minimum width of constricted portions of the recesses to prevent detachment of interlocked projections and recesses.