An ROP attack protection apparatus constituted of: a first region of memory having stored therein a protection function, the first region of memory set as executable; and a second region of memory having stored thereon a plurality of operation functions, the second region of memory set as non-executable, wherein the protection function is arranged to: responsive to a call to one of the plurality of operation functions and further responsive to at least one predetermined rule, allow execution of the called operation function; and after receiving a return from the executed operation function, set the executed operation function as non-executable.