A vital signal measuring apparatus is attached to a living body to measure a vital signal of the living body, which includes an amplifier, an A/D converter, a processing unit, an n-th-order differential signal output unit, and an output unit. The amplifier and the A/D converter constitute a vital signal measuring unit for measuring a vital signal from a vital signal sensor and outputting a first signal corresponding to the vital signal. A time differentiation signal output unit includes the n-th-order differential signal output unit for receiving the first signal and outputting an n-th-order time differentiation signal (where n is an integer of 1 or more) of the first signal. The processing unit functions as a contact condition determination unit for determining contact condition between the vital signal measuring apparatus and the living body based on the n-th-order time differentiation signal.
