  We show that a novel decay mode $Zh$ of the bound state of stop-anti-stop
pair in the ground state $^1S_0(\widetilde t_1\widetilde t_1^*)$ may have a
significant branching ratio if the $CP$ violating mixing appears in the stop
sector, even after we apply the stringent constraint from the measurement of
the electric dipole moment (EDM) of the electron. We show that the branching
ratio can be as large as 10% in some parameter space that it may be detectable
at the LHC.
