An electronic apparatus having a semiconductor integrated circuit and power supplying means, a first circuit and a second circuit being built in the semiconductor integrated circuit, each of the first circuit and the second circuit having a normal mode and a standby mode, the power supplying means being configured to supply power to the semiconductor integrated circuit, the electronic apparatus comprising: power supply controlling means configured to supply power generated by the power supplying means to the second circuit when the operation mode of the semiconductor integrated circuit has changed to the normal mode, and to discontinue supply of power generated by the power supplying means to the second circuit when the operation mode of the semiconductor integrated circuit has changed to the standby mode; characterized in that: the power supply controlling means is configured to supply power generated by the power supplying means to the first circuit through a first regulator when the operation mode of the semiconductor integrated circuit is the normal mode and when the operation mode of the semiconductor integrated circuit is the standby mode; the first circuit comprises a power controlling circuit configured to control supply of power from the power supply controlling means to the second circuit, and mode controlling means configured to change an operation mode of the semiconductor integrated circuit to the normal mode and the standby mode; and wherein respective first and second power supply lines extend between the power supply controlling means and the first circuit and second circuit, and the power controlling circuit is configured to control supply of power from the power supply controlling means to the second circuit through a second regulator by output of a power IC control signal to a power IC control signal line under the control of the mode controlling means for controlling a switch in the second power supply line, wherein the power supply controlling means further comprises a regulator controlling circuit configured to receive the power IC control signal and to generate a control signal for the switch in the power supply controlling means. the power supply controlling means is configured to supply power generated by the power supplying means to the first circuit through a first regulator when the operation mode of the semiconductor integrated circuit is the normal mode and when the operation mode of the semiconductor integrated circuit is the standby mode; the first circuit comprises a power controlling circuit configured to control supply of power from the power supply controlling means to the second circuit, and mode controlling means configured to change an operation mode of the semiconductor integrated circuit to the normal mode and the standby mode; and wherein respective first and second power supply lines extend between the power supply controlling means and the first circuit and second circuit, and the power controlling circuit is configured to control supply of power from the power supply controlling means to the second circuit through a second regulator by output of a power IC control signal to a power IC control signal line under the control of the mode controlling means for controlling a switch in the second power supply line,