PURPOSE: To prepare an optical element having high precision in the process for prepg. an optical element by the reheat press method, by pressing and mold ing and optical element between dies from vertical direction, then shifting the pressing condition in the horizontal direction to remove the dies.

CONSTITUTION: A material for lens 13 softened by heating is held at its periph ery with a member 14 and conveyed into between a pair of die 11, 12 facing each other in the vertical direction. Then, the lens material 13 is pressed from above and below by the dies 11, 12 to form a lens 131 having a desired shape. At this stage, a flange part 132 is formed around the periphery of the lens by a part of the material pressed out of the die 11, 12. Then, the dies 11, 12 are turned by 90° while holding the lens in pressed condition, so the lens is now pressed from the horizontal direction. After holding the flange part 132 with a recovering holding member 115, the dies 11, 12 are separated to the original position, and the lens 131 is taken out. By this method, sticking of fine glass pieces or foreign matters such as dust generated by the shock at the stage of separation of the dies to the surface of the dies, is prevented. Embedding of such material in the surface of the optical element is also prevented.