Thank you.
My PC's CPU support AMD-V, but I installed ESXi to virtualbox guestOS.
Installing VMware vSphere 5 on Virtualbox 4.1 | MyTricks –
http://mytricks.in/2011/09/installing-vmware-vsphere-5-on.html
It maeans we can instal ESXi to Virtualbox guestOS but we can not create the guestOS of that ESXi ?