Provided is a measuring apparatus including: a driving unit that outputs first and second driving signals each having an opposite phase; a first semiconductor laser device, driven by the first driving signal, that emits a first laser beam to an object to be measured; a second semiconductor laser device, disposed near the first device and driven by the second driving signal, that emits a second laser beam to the object; a first detection unit that detects a first electrical signal that corresponds to the intensity of the first laser beam modulated due to the self-coupling effect; a second detection unit that detects a second electrical signal that corresponds to the intensity of the second laser beam modulated due to the self-coupling effect; a calculation unit that calculates differences between the first and second electrical signals; and a measuring unit that measures a state change of the object from the difference.