To provide a code managing device for a BIOS and a BIOS chip capable of managing a code.

A BIOS chip 10 is composed of a first flash memory unit 12 for preserving an inside BIOS, a second flash memory unit 14 for preserving code data, and an integrated code managing device 15 connected to an external device, the first flash memory, and the second flash memory. At the time of receiving a modifying command, the integrated code managing device generates code data, and transmits the code data to the second flash memory unit so that the code data can be preserved. Then, the encipherment of the coded data is executed. At last, the original coded data are compared with the decoded data, and only when the original coded data are coincident with the decoded data, the modification of the inside BIOS is permitted. The encipherment is made excutable by using asymmetrical RSA engines so that it is impossible to find out any correct RSA code. Therefore, it is possible to protect the inside BIOS data from modification due to the intrusion of any virus program.