A cylinder lubricating oil composition for a crosshead diesel engine equipped with a scrubber, comprising: a base oil; and (A) a metallic detergent, wherein the lubricating oil composition has a base number measured by the perchloric acid method of 15 to 125 mgKOH/g, and a kinematic viscosity at 100°C of 10 to 30 mm 2 /s; and wherein the lubricating oil composition comprises, as the component (A), (A1) a Ca phenate detergent; and (A2) a metallic detergent other than any Ca phenate detergent; the lubricating oil composition optionally comprises: (C-1') a succinimide having at least one alkyl or alkenyl group in a molecule thereof, or a borated derivative thereof, in an amount of no more than 0.015 mass% in terms of nitrogen on the basis of the total mass of the composition; and wherein a Ph value represented by the following formula is no more than 20 × 10 -3 : Ph value = C Ca × 2 / r M × 40.08 wherein in the formula , C Ca represents calcium content in mass% derived from the component (A1), and r M represents a metal ratio of the component (A1); and wherein the metal ratio of component (A1) is calculated by the following formula : metal ratio of component A 1 = calcium content in mass % in Ca phenate detergent which is component A 1 / calcium content in mass % derived from soap base in Ca phenate detergent which is component A 1 (A) a metallic detergent, wherein the lubricating oil composition has a base number measured by the perchloric acid method of 15 to 125 mgKOH/g, and a kinematic viscosity at 100°C of 10 to 30 mm 2 /s; and wherein the lubricating oil composition comprises, as the component (A), (A1) a Ca phenate detergent; and (A2) a metallic detergent other than any Ca phenate detergent; the lubricating oil composition optionally comprises: (C-1') a succinimide having at least one alkyl or alkenyl group in a molecule thereof, or a borated derivative thereof, in an amount of no more than 0.015 mass% in terms of nitrogen on the basis of the total mass of the composition; and wherein a Ph value represented by the following formula is no more than 20 × 10 -3 : Ph value = C Ca × 2 / r M × 40.08 wherein in the formula , C Ca represents calcium content in mass% derived from the component (A1), and r M represents a metal ratio of the component (A1); and wherein the metal ratio of component (A1) is calculated by the following formula : metal ratio of component A 1 = calcium content in mass % in Ca phenate detergent which is component A 1 / calcium content in mass % derived from soap base in Ca phenate detergent which is component A 1 wherein the lubricating oil composition has a base number measured by the perchloric acid method of 15 to 125 mgKOH/g, and a kinematic viscosity at 100°C of 10 to 30 mm 2 /s; and wherein the lubricating oil composition comprises, as the component (A), (A1) a Ca phenate detergent; and (A2) a metallic detergent other than any Ca phenate detergent; (A1) a Ca phenate detergent; and (A2) a metallic detergent other than any Ca phenate detergent; the lubricating oil composition optionally comprises: (C-1') a succinimide having at least one alkyl or alkenyl group in a molecule thereof, or a borated derivative thereof, in an amount of no more than 0.015 mass% in terms of nitrogen on the basis of the total mass of the composition; and wherein a Ph value represented by the following formula is no more than 20 × 10 -3 : Ph value = C Ca × 2 / r M × 40.08 wherein in the formula , C Ca represents calcium content in mass% derived from the component (A1), and r M represents a metal ratio of the component (A1); and wherein the metal ratio of component (A1) is calculated by the following formula : metal ratio of component A 1 = calcium content in mass % in Ca phenate detergent which is component A 1 / calcium content in mass % derived from soap base in Ca phenate detergent which is component A 1 <EOS>