A transistor includes a substrate; a pair of constant current forming regions provided in the substrate; a pair of source/drain regions respectively provided on the pair of constant current forming regions in the substrate; and a gate structure provided between the pair of source/drain regions, wherein any one of the constant current forming regions immediately adjacent to any one of the pair of source/drain regions serving as a drain forms a constant current between the any one of the pair of source/drain region serving as the drain and the any one of the constant current forming regions.