A voltage trimming circuit including: a first resistance circuit having a first resistance value determined by up codes and down codes; a second resistance circuit having a second resistance value determined by the up codes and the down codes; and a comparator to output a voltage detection signal by comparing a voltage level of a reference voltage trimming node to that of a feedback node, wherein the voltage detection signal adjusts the up and down codes, which increase the first resistance value and decrease the second resistance value when the voltage level of the reference voltage trimming node is higher than that of the feedback node, and adjusts the up and down codes, which decrease the first resistance value and increase the second resistance value when the voltage level of the reference voltage trimming node is lower than that of the feedback node.