A probe insertion device for a neural probe structure with a plurality of probes to simultaneously insert the plurality of probes into a nerve includes a nerve holder to fix the nerve surrounding an outer circumference of the nerve, and a probe holder positioned outside in a radial direction of the nerve holder to fixedly support the probes surrounding a circumference of the nerve holder. The probe holder includes a plurality of sections (“probe holder sections”) arranged radially with respect to the nerve holder and moveable in a radial direction of the nerve holder, and the plurality of probe holder sections simultaneously moves the plurality of probes toward the nerve holder having fixed the nerve, so that the plurality of probes is simultaneously inserted into the nerve in a radial shape when viewed in a lengthwise direction of the nerve.