Semiconductor integrated circuit

A semiconductor integrated circuit comprising:

• a first power supply line;
• a first switch which is put into ON state to supply a first voltage to said first power supply line;
• a second power supply line;
• a voltage dropping circuit, arranged between said first power supply line and said second power supply line, for supplying said first power supply line with a voltage which is obtained by dropping the voltage of said second power supply line, when said first switch is put into OFF state;
• a third power supply line which is set to a second voltage lower than said first voltage;
• a fourth power supply line;
• a voltage generating circuit for generating a third voltage lower than said second voltage, to supply said third voltage to said fourth power supply line when said first switch is put into OFF state, said voltage generating circuit generating a voltage higher than said third voltage and supplying said voltage to said fourth power supply line when said first switch is put into ON state;
• and
• an internal circuit including a p-channel field effect transistor and an n-channel field effect transistor, said p-channel field effect transistor having a source terminal and a substrate electrode which are connected to said first power supply line and said second power supply line, respectively, said n-channel field effect transistor having a source terminal and a substrate electrode which are connected to said third power supply line and said fourth power supply line, respectively.