An electric device comprising an electric device body and a battery pack, wherein the battery pack comprises: a rechargeable battery; a battery information memory unit configured to store battery type information relating to a type of the rechargeable battery, wherein the battery type information includes information relating to a material of the rechargeable battery; a charging control unit configured to measure the number of charge/discharge cycles of the rechargeable battery and to store the number of charge/discharge cycles in the battery information memory unit; and an information output unit configured to output the battery type information from the battery pack, wherein the information output unit is configured to output the battery type information including the number of charge/discharge cycles from the battery pack; and wherein the electric device body comprises: a control unit configured to obtain the information which is outputted from the information output unit; and a residual capacity calculation unit configured to calculate a residual capacity of the rechargeable battery based on voltage capacity information corresponding to the type of the rechargeable battery according to the battery type information and based on the number of charge/discharge cycles for the rechargeable battery, the voltage capacity information being stored in the battery information memory unit of the battery pack or in a capacity information memory unit of the electric device body and indicating the relationship between a battery voltage of the rechargeable battery and a residual capacity of the rechargeable battery. a rechargeable battery; a battery information memory unit configured to store battery type information relating to a type of the rechargeable battery, wherein the battery type information includes information relating to a material of the rechargeable battery; a charging control unit configured to measure the number of charge/discharge cycles of the rechargeable battery and to store the number of charge/discharge cycles in the battery information memory unit; and an information output unit configured to output the battery type information from the battery pack, wherein the information output unit is configured to output the battery type information including the number of charge/discharge cycles from the battery pack; and wherein the electric device body comprises: a control unit configured to obtain the information which is outputted from the information output unit; and a residual capacity calculation unit configured to calculate a residual capacity of the rechargeable battery based on voltage capacity information corresponding to the type of the rechargeable battery according to the battery type information and based on the number of charge/discharge cycles for the rechargeable battery, the voltage capacity information being stored in the battery information memory unit of the battery pack or in a capacity information memory unit of the electric device body and indicating the relationship between a battery voltage of the rechargeable battery and a residual capacity of the rechargeable battery. a control unit configured to obtain the information which is outputted from the information output unit; and a residual capacity calculation unit configured to calculate a residual capacity of the rechargeable battery based on voltage capacity information corresponding to the type of the rechargeable battery according to the battery type information and based on the number of charge/discharge cycles for the rechargeable battery, the voltage capacity information being stored in the battery information memory unit of the battery pack or in a capacity information memory unit of the electric device body and indicating the relationship between a battery voltage of the rechargeable battery and a residual capacity of the rechargeable battery.