Abstract: Straight travelling apparatus for construction vehicles capable of keeping the construction vehicle travelling straight even when a work implement of the construction vehicle is manipulated during travelling. The apparatus includes hydraulic circuitry for making the hydraulic oil of first and second pumps be supplied to left and right travelling motors respectively when only the left and right travelling motors are operated, and making the oils be confluent together and equally distributed and supplied to the left and right travelling motors when even one work implement is to be manipulated at the same time as operating the left and right travelling motors. The hydraulic circuitry includes left and right directional selecting valves and a confluent line extending between the directional selecting valves for selectively making the hydraulic oil confluent together.