A bio-signal sensor is provided, including: a dry electrode having a plurality of probes and a plurality of contacts correspondingly and electrically connected to the probes, wherein each of the probes senses and transmits an electrical signal to the corresponding contact and a kit replaceably disposed between the dry electrode and a bio-signal measurement device and having a functional circuit for capturing the electrical signals from the contacts so as to generate a bio-signal and a signal output terminal electrically connected to the functional circuit for transmitting the bio-signal to the bio-signal measurement device.
