A hydraulic unit of an electronic control brake system including a modulator block a pair of master cylinder connection portions a first valve row having a plurality of first valve accommodation bores a second valve row having a plurality of second valve accommodation bores a pair of low-pressure accumulator bores arranged in a bottom side of the modulator block in the lateral direction pump accommodation bores a pair of shuttle valve ESV accommodation bores arranged between the first valve row and the second valve row a pair of driving force control valve TC accommodation bores arranged between wheel cylinder connection portions formed in the modulator block and the first valve row and a pair of high-pressure accumulator bores arranged in the modulator block in a longitudinal direction, wherein the pair of high-pressure accumulator bores are formed to have an arrangement parallel to the motor accommodation bores.
