A free-cutting copper alloy worked material comprising: 75.0 mass% to 78.5 mass% of Cu; 2.95 mass% to 3.55 mass% of Si; 0.07 mass% to 0.28 mass% of Sn; 0.06 mass% to 0.14 mass% of P; 0.022 mass% to 0.25 mass% of Pb; less than 0.06 mass% of Ni; optionally one or more element(s) selected from the group consisting of 0.02 mass% to 0.08 mass% of Sb, 0.02 mass% to 0.08 mass% of As, and 0.02 mass% to 0.30 mass% of Bi; and the balance being Zn and inevitable impurities, wherein the total amount of Fe, Mn, Co, and Cr as the inevitable impurities is lower than 0.08 mass%, when the Cu content is represented by [Cu] mass%, the Si content is represented by [Si] mass%, the Sn content is represented by [Sn] mass%, the P content is represented by mass%, and the Pb content is represented by [Pb] mass%, the relations of 76.2 ≤ f 1 = Cu + 0.8 × Si − 8.5 × Sn + P + 0.5 × Pb ≤ 80.3 and 61.5 ≤ f2 = Cu − 4.3 × Si − 0.7 × Sn − P + 0.5 × Pb ≤ 63.3 are satisfied, in constituent phases of metallographic structure, when the area ratio of α phase is represented by (α)%, the area ratio of β phase is represented by (β)%, the area ratio of γ phase is represented by (γ)%, the area ratio of κ phase is represented by (κ)%, and the area ratio of μ phase is represented by (μ) %, relative to the total area ratio of α phase, β phase, γ phase, δ phase, ε phase, ζ phase, η phase, κ phase, μ phase and χ phase, the relations of 25 ≤ κ ≤ 65, 0 ≤ γ ≤ 1.5, 0 ≤ β ≤ 0.2, 0 ≤ μ ≤ 2.0, 97.0 ≤ f3 = α + κ, 99.4 ≤ f4 = α + κ + γ + μ, 0 ≤ f5 = γ + μ ≤ 2.5, and 27 ≤ f6 = κ + 6 × γ 1 / 2 + 0.5 × μ ≤ 70 are satisfied, the length of the long side of γ phase is 40 μm or less, the length of the long side of μ phase is 25 μm or less, the amount of Sn in κ phase is 0.08 mass% to 0.45 mass%, the amount of P in κ phase is 0.07 mass% to 0.24 mass%, and κ1 phase is present in α phase and has a thickness of 0.05 μm to 0.5 μm, and therein the microstructural features as well as the Sn and P contents in κ phase are determined according to the respective methods disclosed in the description. 75.0 mass% to 78.5 mass% of Cu; 2.95 mass% to 3.55 mass% of Si; 0.07 mass% to 0.28 mass% of Sn; 0.06 mass% to 0.14 mass% of P; 0.022 mass% to 0.25 mass% of Pb; less than 0.06 mass% of Ni; optionally one or more element(s) selected from the group consisting of 0.02 mass% to 0.08 mass% of Sb, 0.02 mass% to 0.08 mass% of As, and 0.02 mass% to 0.30 mass% of Bi; and the balance being Zn and inevitable impurities, wherein the total amount of Fe, Mn, Co, and Cr as the inevitable impurities is lower than 0.08 mass%, when the Cu content is represented by [Cu] mass%, the Si content is represented by [Si] mass%, the Sn content is represented by [Sn] mass%, the P content is represented by mass%, and the Pb content is represented by [Pb] mass%, the relations of 76.2 ≤ f 1 = Cu + 0.8 × Si − 8.5 × Sn + P + 0.5 × Pb ≤ 80.3 and 61.5 ≤ f2 = Cu − 4.3 × Si − 0.7 × Sn − P + 0.5 × Pb ≤ 63.3 are satisfied, in constituent phases of metallographic structure, when the area ratio of α phase is represented by (α)%, the area ratio of β phase is represented by (β)%, the area ratio of γ phase is represented by (γ)%, the area ratio of κ phase is represented by (κ)%, and the area ratio of μ phase is represented by (μ) %, relative to the total area ratio of α phase, β phase, γ phase, δ phase, ε phase, ζ phase, η phase, κ phase, μ phase and χ phase, the relations of 25 ≤ κ ≤ 65, 0 ≤ γ ≤ 1.5, 0 ≤ β ≤ 0.2, 0 ≤ μ ≤ 2.0, 97.0 ≤ f3 = α + κ, 99.4 ≤ f4 = α + κ + γ + μ, 0 ≤ f5 = γ + μ ≤ 2.5, and 27 ≤ f6 = κ + 6 × γ 1 / 2 + 0.5 × μ ≤ 70 are satisfied, the length of the long side of γ phase is 40 μm or less, the length of the long side of μ phase is 25 μm or less, the amount of Sn in κ phase is 0.08 mass% to 0.45 mass%, the amount of P in κ phase is 0.07 mass% to 0.24 mass%, and κ1 phase is present in α phase and has a thickness of 0.05 μm to 0.5 μm, and therein the microstructural features as well as the Sn and P contents in κ phase are determined according to the respective methods disclosed in the description.