PURPOSE: To incorporate the title RAM on a circuit board at the same integration density as a static RAM not provided with a backup function by a method wherein a circuit element for backup power-supply use is built in an IC chip and a housing part for a backup power supply is formed in a package with which the circuit element is covered.

CONSTITUTION: A housing part 40 for a backup power supply 12 which backs up a main power supply is formed on the lower side face 38 of a package 2; battery terminals 30, 32 composed of wide faces of frame terminals used to supply the backup power supply 12 are arranged in a state that they are faced with the upper and lower inner faces of the housing part 40. The backup power supply 12 such as a battery or the like which is oval-shaped is housed inside the housing part 40. Thereby, although the title RAM is provided with a backup function, it can be incorporated at the same integration density as a static RAM having a structure not provided with any backup function.