A lock mechanism for a stage apparatus, includes a stationary support
board; a movable stage; a leaf spring supported by the stationary support
board; a press portion and a pressed portion provided on the leaf spring
and the movable stage, respectively, a frictional contacting member being
fixed to at least one of opposed surfaces of the press portion and the
pressed portion; an electromagnet for resiliently deforming the leaf
spring in a lock releasing direction to disengage the frictional
contacting member from the one of opposed surfaces of the press portion
and the pressed portion; and a permanent magnet, fixed to the stationary
support board, which magnetically attracts the leaf spring to hold the
frictional contacting member and the one of opposed surfaces of the press
portion and the pressed portion in a disengaged state when the leaf
spring is resiliently deformed by the electromagnet.