Provided is an oscillator using an MEMS resonator, which can reduce an influence of noise of a TIA and improve phase noise characteristics of an oscillator output. The oscillator includes an MEMS resonator, a TIA, a buffer amplifier, and a current/voltage converter that couples, by electromagnetic induction, with a wiring line via which an output of the MEMS resonator is fed to the TIA, so as to convert a current flowing in the wiring line to a voltage and output the voltage to the buffer amplifier. Thus, the oscillator output is extracted from the current/voltage converter. Further, the current/voltage converter is provided in the form of an oscillation output coil provided so as to surround the wiring line in a noncontact manner, in which oscillation output coil one end is connected to ground and the other end is connected to the buffer amplifier.