A hydraulic circuit for a construction machine (100, 110), the hydraulic circuit including a hydraulic pump (P, P1, P2) and a center bypass passage (RC, RC1, RC2), into which a pressurized oil discharged from the hydraulic pump (P, P1, P2) connected to the center bypass passage (RC, RC1, RC2) is supplied, the hydraulic circuit further comprising: a directional control valve group (Gv) including a plurality of directional control valves (Va1, Va2, Vb1, Vb2, Vbk, Vsw, Vop, Vt1, Vt2) arranged in tandem with and connected to the center bypass passage (RC, RC1, RC2); and a bleed-off valve (Vbo) arranged in the center bypass passage (RC, RC1, RC2) on a downstream side of the directional control valve group (Gv), wherein each directional control valve (Va1, Va2, Vb1, Vb2, Vbk, Vsw, Vop, Vt1, Vt2) includes a first internal passage for causing the pressurized oil supplied to the directional control valve (Va1, Va2, Vb1, Vb2, Vbk, Vsw, Vop, Vt1, Vt2) to flow out to the center bypass passage (RC, RC1, RC2) and a second internal passage for supplying the pressurized oil to a cylinder port (Cprt, CprtA, CprtB), wherein a parallel passage is formed by the center bypass passage (RC, RC1, RC2) and the first internal passage by causing, by the first internal passage, the pressurized oil discharged from the hydraulic pump (P, P1, P2) to flow out to the center bypass passage (RC, RC1, RC2) on the downstream side of the directional control valve (Va1, Va2, Vb1, Vb2, Vbk, Vsw, Vop, Vt1, Vt2), wherein the second internal passage includes a passage for changing a flow rate of the pressurized oil supplied to the cylinder port (Cprt, CprtA, CprtB) in response to a change in an area of an opening of a spool of each directional control valve (Va1, Va2, Vb1, Vb2, Vbk, Vsw, Vop, Vt1, Vt2) and a bypass passage (RBp) for supplying the pressurized oil to the cylinder port (Cprt, CprtA, CprtB) without passing though the opening of the spool; wherein a bypass switching valve (Vps) is connected to the bypass passage (RBp); wherein the second internal passage supplies the pressurized oil from the center bypass passage (RC, RC1, RC2) through the opening of the spool and/or the bypass passage (RBp) to the cylinder port (Cprt, CprtA, CprtB). a directional control valve group (Gv) including a plurality of directional control valves (Va1, Va2, Vb1, Vb2, Vbk, Vsw, Vop, Vt1, Vt2) arranged in tandem with and connected to the center bypass passage (RC, RC1, RC2); and a bleed-off valve (Vbo) arranged in the center bypass passage (RC, RC1, RC2) on a downstream side of the directional control valve group (Gv), wherein each directional control valve (Va1, Va2, Vb1, Vb2, Vbk, Vsw, Vop, Vt1, Vt2) includes a first internal passage for causing the pressurized oil supplied to the directional control valve (Va1, Va2, Vb1, Vb2, Vbk, Vsw, Vop, Vt1, Vt2) to flow out to the center bypass passage (RC, RC1, RC2) and a second internal passage for supplying the pressurized oil to a cylinder port (Cprt, CprtA, CprtB), wherein a parallel passage is formed by the center bypass passage (RC, RC1, RC2) and the first internal passage by causing, by the first internal passage, the pressurized oil discharged from the hydraulic pump (P, P1, P2) to flow out to the center bypass passage (RC, RC1, RC2) on the downstream side of the directional control valve (Va1, Va2, Vb1, Vb2, Vbk, Vsw, Vop, Vt1, Vt2), wherein the second internal passage includes a passage for changing a flow rate of the pressurized oil supplied to the cylinder port (Cprt, CprtA, CprtB) in response to a change in an area of an opening of a spool of each directional control valve (Va1, Va2, Vb1, Vb2, Vbk, Vsw, Vop, Vt1, Vt2) and a bypass passage (RBp) for supplying the pressurized oil to the cylinder port (Cprt, CprtA, CprtB) without passing though the opening of the spool; wherein a bypass switching valve (Vps) is connected to the bypass passage (RBp); wherein the second internal passage supplies the pressurized oil from the center bypass passage (RC, RC1, RC2) through the opening of the spool and/or the bypass passage (RBp) to the cylinder port (Cprt, CprtA, CprtB).