An object of the present invention is to a provide tamper resistant information processing unit that is used as an IC card with a high level of security.To achieve the above-mentioned object, the information unit of the present invention comprises: a program container part for storing a program; a memory for storing data; an arithmetic unit for performing specified processing according to the program; a data bus for connecting the memory to the arithmetic unit; and a transform function for transforming a logical address and a physical address of the memory, said logical address being used for arithmetic operation by the arithmetic unit, said physical address being set at random corresponding to the logical address at each arithmetic operation or every time the information processing unit is started up.