To provide an oscillation circuit which can measure leak currents.

The oscillation circuit is provided with: external terminals 1 and 2 to which an oscillator X is externally connected; an inverter circuit I1 connected between the terminals 1 and 2; a switch element S0 which has one end connected to the external terminal 1 and is turned on/off according to an input signal from an internal terminal N0; built-in feedback resistances Rfi1 and Rfi2 connected between the other end of the switch element S0 and the external terminal 2; a switch element S1 connected in parallel with the built-in feedback resistance Rfi1 and to be turned on/off according to an input control signal from the internal terminal N1; and a switch element S2 connected in parallel with the built-in feedback resistance Rfin2 and to be turned on/off according to an input control signal from the internal terminal N2, wherein the switch element S0 is turned off to insulate the external terminal 1 from the output of the inverter circuit I1, so that the leak currents of the external terminal 1 can be measured.