The history and present status of "antimatter" study at CERN's antiproton decelerator (AD) facility are presented.  The AD is a synchrotron which decelerates some 10 million antiprotons from 3 GeV to 5 MeV in 100 seconds, and has been in operation since 2000.  Among various physics programs, laser spectroscopy of antihydrogen atoms, and laser spectroscopy of antiprotonic helium atoms, both contribute to the precision tests of CPT symmetry, are discussed in detail. The status of a new post-decelerator, called ELENA, which decelerates antiprotons from 5 MeV to 100 keV and is expected to start operation after CERN's LS2 (long shutdown 2) will be also discussed.