A vehicle comprising an internal combustion engine mounted thereon with center lines of a plurality of cylinders inclined with respect to an up to down direction of the vehicle, the internal combustion engine including: a variable valve timing mechanism configured by winding a timing chain thereon; a hydraulic control valve controlling hydraulic oil supplied to the variable valve timing mechanism; and a chain casing fixed to a cylinder head to cover the timing chain and the variable valve timing mechanism, wherein the chain casing includes: a bulging portion bulging in a crank shaft direction and covering the variable valve timing mechanism; and a cylindrical cylinder portion attaching the hydraulic control valve thereto, wherein the hydraulic control valve includes: a small diameter portion inserted from an upper end of the cylinder portion in an axial direction thereof into the cylinder portion, the upper end being open; and a large diameter portion exposed from the upper end of the cylinder portion in the axial direction, wherein the cylinder portion is adjacently formed below the bulging portion, wherein the other end portion of the cylinder portion in the axial direction is located below the upper end of the cylinder portion in the axial direction, wherein the chain casing includes a connection rib to connect the other end portion of the cylinder portion in the axial direction to the bulging portion, and wherein the chain casing includes a reinforcement rib extending in the axial direction of the cylinder portion from the upper end of the cylinder portion in the axial direction to at least a position above the large diameter portion along an end portion on the side opposite to the bulging portion in the cylinder portion. a variable valve timing mechanism configured by winding a timing chain thereon; a hydraulic control valve controlling hydraulic oil supplied to the variable valve timing mechanism; and a chain casing fixed to a cylinder head to cover the timing chain and the variable valve timing mechanism, wherein the chain casing includes: a bulging portion bulging in a crank shaft direction and covering the variable valve timing mechanism; and a cylindrical cylinder portion attaching the hydraulic control valve thereto, a bulging portion bulging in a crank shaft direction and covering the variable valve timing mechanism; and a cylindrical cylinder portion attaching the hydraulic control valve thereto, wherein the hydraulic control valve includes: a small diameter portion inserted from an upper end of the cylinder portion in an axial direction thereof into the cylinder portion, the upper end being open; and a large diameter portion exposed from the upper end of the cylinder portion in the axial direction, a small diameter portion inserted from an upper end of the cylinder portion in an axial direction thereof into the cylinder portion, the upper end being open; and a large diameter portion exposed from the upper end of the cylinder portion in the axial direction, wherein the cylinder portion is adjacently formed below the bulging portion, wherein the other end portion of the cylinder portion in the axial direction is located below the upper end of the cylinder portion in the axial direction, wherein the chain casing includes a connection rib to connect the other end portion of the cylinder portion in the axial direction to the bulging portion, and wherein the chain casing includes a reinforcement rib extending in the axial direction of the cylinder portion from the upper end of the cylinder portion in the axial direction to at least a position above the large diameter portion along an end portion on the side opposite to the bulging portion in the cylinder portion.