A hydraulic circuit for a construction machine, comprising: a hydraulic pump (P; P1, P2); a center bypass passage (RC; RC1, RC2; a direction control valve group (Gv) including a plurality of direction control valves (V; Va1, Vb2, Vsw, Vop, Vt1; Va2, Vb1, Vbk, Vt2, Vst) that are provided to the center bypass passage (RC; RC1, RC2; a bleed-off valve (Vbo) provided to the center bypass passage (RC; RC1, RC2) downstream of the direction control valve group (Gv); and wherein a given directional control valve of the plurality of direction control valves includes a first internal passage that is configured to discharge the pressure oil supplied to the given direction control valve (Va1, Va2) to the center bypass passage (RC; RC1, RC2), and a second internal passage that is adapted to supply the pressure oil to a hydraulic actuator of the construction machine, wherein the first internal passage causes pressure oil discharged from the hydraulic pump (P; P1, P2) to flow out to the center bypass passage (RC; RC1, RC2) downstream of the given direction control valve (Va1, Va2) regardless of a spool position of the given direction control valve (Va1, Va2), so that the center bypass passage (RC; RC1, RC2) and the first internal passage form a parallel passage, wherein the bleed-off valve (Vbo) is adapted to perform bleed-off control on pressure oil supplied by way of the parallel passage by changing an opening area of the bleed-off valve (Vbo), characterized in that a control valve (Vth; Vth1, Vth2) is provided upstream of and is connected to the given direction control valve (Va1, Va2) and is adapted to control the amount of the pressure oil to be supplied from the center bypass passage (RC; RC1, RC2) to the second internal passage of the given direction control valve (Va1, Va2) by changing an opening degree of the control valve (Vth; Vth1, Vth2). a hydraulic pump (P; P1, P2); a center bypass passage (RC; RC1, RC2; a direction control valve group (Gv) including a plurality of direction control valves (V; Va1, Vb2, Vsw, Vop, Vt1; Va2, Vb1, Vbk, Vt2, Vst) that are provided to the center bypass passage (RC; RC1, RC2; a bleed-off valve (Vbo) provided to the center bypass passage (RC; RC1, RC2) downstream of the direction control valve group (Gv); and wherein a given directional control valve of the plurality of direction control valves includes a first internal passage that is configured to discharge the pressure oil supplied to the given direction control valve (Va1, Va2) to the center bypass passage (RC; RC1, RC2), and a second internal passage that is adapted to supply the pressure oil to a hydraulic actuator of the construction machine, wherein the first internal passage causes pressure oil discharged from the hydraulic pump (P; P1, P2) to flow out to the center bypass passage (RC; RC1, RC2) downstream of the given direction control valve (Va1, Va2) regardless of a spool position of the given direction control valve (Va1, Va2), so that the center bypass passage (RC; RC1, RC2) and the first internal passage form a parallel passage, wherein the bleed-off valve (Vbo) is adapted to perform bleed-off control on pressure oil supplied by way of the parallel passage by changing an opening area of the bleed-off valve (Vbo), characterized in that a control valve (Vth; Vth1, Vth2) is provided upstream of and is connected to the given direction control valve (Va1, Va2) and is adapted to control the amount of the pressure oil to be supplied from the center bypass passage (RC; RC1, RC2) to the second internal passage of the given direction control valve (Va1, Va2) by changing an opening degree of the control valve (Vth; Vth1, Vth2). wherein a given directional control valve of the plurality of direction control valves includes a first internal passage that is configured to discharge the pressure oil supplied to the given direction control valve (Va1, Va2) to the center bypass passage (RC; RC1, RC2), and a second internal passage that is adapted to supply the pressure oil to a hydraulic actuator of the construction machine, wherein the first internal passage causes pressure oil discharged from the hydraulic pump (P; P1, P2) to flow out to the center bypass passage (RC; RC1, RC2) downstream of the given direction control valve (Va1, Va2) regardless of a spool position of the given direction control valve (Va1, Va2), so that the center bypass passage (RC; RC1, RC2) and the first internal passage form a parallel passage, wherein the bleed-off valve (Vbo) is adapted to perform bleed-off control on pressure oil supplied by way of the parallel passage by changing an opening area of the bleed-off valve (Vbo), characterized in that a control valve (Vth; Vth1, Vth2) is provided upstream of and is connected to the given direction control valve (Va1, Va2) and is adapted to control the amount of the pressure oil to be supplied from the center bypass passage (RC; RC1, RC2) to the second internal passage of the given direction control valve (Va1, Va2) by changing an opening degree of the control valve (Vth; Vth1, Vth2).