An object information acquiring apparatus includes a detector including m-number of probes to which a voltage is supplied and a current/voltage conversion circuit which converts a current into a voltage, a receiver processing electric signals from the probes, and a relay board respectively relaying power distribution lines between the electrical power source and the probes and signal wirings between the receiver and the probe, wherein the relay board receives input of signal wirings and power distribution lines from n-number (m≧n) of probes among the m-number of probes, connects the signal wirings from the n-number of probes to the receiver, and connects, to the electrical power source side, the power distribution lines of a number that is fewer than the power distribution lines from the n-number of probes.
