A valve lifter for a three-dimensional cam and a variable valve operating
apparatus have enhanced flexibility in the design of a detent mechanism of
the valve lifter for the three-dimensional cam, as well as enhanced
durability. It is possible to form a thick wall portion which is
sufficiently thick without increasing the weight by providing an offset
between an outer peripheral surface and an inner peripheral surface of the
valve lifter. Therefore, a sufficiently large projection can be mounted
without deforming the valve lifter. This structure makes it possible to
increase an area contacting a detent groove, reduce the surface pressure,
and enhance the durability. The thick wall portion exists longer in an
axial direction of the valve lifter, so the detent mechanism can be formed
on the outer peripheral surface instead of a top surface. Therefore, the
flexibility of design of the detent mechanism can be enhanced.