A bio signal measuring device for measuring bio signals of fish comprising: a fixing unit for fixing fish, wherein the fixing unit comprises a fish seat having a groove corresponding to the shape of the fish so that the fish is fixed therein; an electrode unit configured to be attached to the fish to measure a bio signal of the fish; characterized in that the bio signal measuring device further comprises: a medicine storage unit for storing medicines to be supplied to the fish fixed on the fixing unit, wherein the medicine storage unit includes a plurality of medicine storages for storing different medicines, and one of the medicine storages keeps liquid containing dissolved oxygen to be supplied to the fish so that the fish is enabled to keep breathing and alive when an examination is in progress or even when not; a medicine mixing unit for mixing the medicines provided from the medicine storage unit; a medicine distribution unit for receiving the mixed medicines from the medicine mixing unit and distributing the mixed medicines to each of a plurality of fish; a needle unit injecting the medicines distributed from the medicine distribution unit to each fish, wherein the needle unit comprises an oral needle connected to the medicine distribution unit to receive the medicine and configured to be inserted into the mouth of the fish to inject the medicines. a fixing unit for fixing fish, wherein the fixing unit comprises a fish seat having a groove corresponding to the shape of the fish so that the fish is fixed therein; an electrode unit configured to be attached to the fish to measure a bio signal of the fish; characterized in that the bio signal measuring device further comprises: a medicine storage unit for storing medicines to be supplied to the fish fixed on the fixing unit, wherein the medicine storage unit includes a plurality of medicine storages for storing different medicines, and one of the medicine storages keeps liquid containing dissolved oxygen to be supplied to the fish so that the fish is enabled to keep breathing and alive when an examination is in progress or even when not; a medicine mixing unit for mixing the medicines provided from the medicine storage unit; a medicine distribution unit for receiving the mixed medicines from the medicine mixing unit and distributing the mixed medicines to each of a plurality of fish; a needle unit injecting the medicines distributed from the medicine distribution unit to each fish, wherein the needle unit comprises an oral needle connected to the medicine distribution unit to receive the medicine and configured to be inserted into the mouth of the fish to inject the medicines. a medicine storage unit for storing medicines to be supplied to the fish fixed on the fixing unit, wherein the medicine storage unit includes a plurality of medicine storages for storing different medicines, and one of the medicine storages keeps liquid containing dissolved oxygen to be supplied to the fish so that the fish is enabled to keep breathing and alive when an examination is in progress or even when not; a medicine mixing unit for mixing the medicines provided from the medicine storage unit; a medicine distribution unit for receiving the mixed medicines from the medicine mixing unit and distributing the mixed medicines to each of a plurality of fish; a needle unit injecting the medicines distributed from the medicine distribution unit to each fish, wherein the needle unit comprises an oral needle connected to the medicine distribution unit to receive the medicine and configured to be inserted into the mouth of the fish to inject the medicines.