An antenna-apparatus connection circuit provided with an antenna apparatus connector connected to an antenna apparatus, and a power terminal, the antenna-apparatus connection circuit comprising: a first switching element having a control end, a first end, and a second end; a second switching element having a control end, a first end, and a second end; a first resistance having a first end connected to the power terminal; and a second resistance having a first end connected to the ground, wherein the first end of the first switching element is connected to the second end of the first resistance, the second end of the first switching element is connected to the antenna apparatus connector, the first end of the second switching element is connected to the second end of the second resistance, the second end of the second switching element is connected to the control end of the first switching element, and the control end of the second switching element is connected to the second end of the first switching element, wherein the antenna-apparatus connection circuit further comprises a third switching element having a control end, a first end, and a second end, and a third resistance having a first end connected to the control end of the first switching element, wherein the first end of the third switching element is connected to the power terminal, the second end of the third switching element is connected to the first end of the second switching element, the control end of the third switching element is connected to the second end of the third resistance, and a fourth resistance is connected between the first end and the second end of the first switching element, and wherein, when an impedance of the antenna apparatus is equal to or larger than a minimum value of a predetermined proper impedance, the third switching element is turned off, and the first switching element is turned on, whereas, when the impedance of the antenna apparatus is smaller than the minimum value of the proper impedance, the third switching element is turned on, and the first switching element is turned off. a first switching element having a control end, a first end, and a second end; a second switching element having a control end, a first end, and a second end; a first resistance having a first end connected to the power terminal; and a second resistance having a first end connected to the ground, wherein the first end of the first switching element is connected to the second end of the first resistance, the second end of the first switching element is connected to the antenna apparatus connector, the first end of the second switching element is connected to the second end of the second resistance, the second end of the second switching element is connected to the control end of the first switching element, and the control end of the second switching element is connected to the second end of the first switching element, wherein the antenna-apparatus connection circuit further comprises a third switching element having a control end, a first end, and a second end, and a third resistance having a first end connected to the control end of the first switching element, a third switching element having a control end, a first end, and a second end, and a third resistance having a first end connected to the control end of the first switching element, wherein the first end of the third switching element is connected to the power terminal, the second end of the third switching element is connected to the first end of the second switching element, the control end of the third switching element is connected to the second end of the third resistance, and a fourth resistance is connected between the first end and the second end of the first switching element, and wherein, when an impedance of the antenna apparatus is equal to or larger than a minimum value of a predetermined proper impedance, the third switching element is turned off, and the first switching element is turned on, whereas, when the impedance of the antenna apparatus is smaller than the minimum value of the proper impedance, the third switching element is turned on, and the first switching element is turned off.