An engine with an oil cooler and an oil filter comprising: an oil gallery; a base attaching seat provided in an engine frame wall; and a base for component mounting attached to the base attaching seat; wherein the oil cooler and the oil filter are mounted on the base for component mounting, and the base attaching seat is provided with an oil inlet communicating with an upstream-side passage of the oil gallery, and an oil outlet communicating with a downstream-side passage of the oil gallery, by attaching the base for component mounting to the base attaching seat, engine oil flowing into the oil inlet of the base attaching seat from the upstream-side passage of the oil gallery passes the base for component mounting, the oil cooler, and the oil filter, and flows out of the oil outlet of the base attaching seat to the downstream-side passage of the oil gallery, the base for component mounting includes a seating portion configured to seat the base attaching seat thereon and an oil cooler attaching seat configured to attach the oil cooler thereto, the seating portion of the base for component mounting includes an oil inlet chamber connected to the oil inlet of the base attaching seat, and the oil cooler attaching seat includes an oil outlet of the oil inlet chamber into which the oil inlet pipe of the oil cooler is inserted and a reentry oil inlet into which the oil outlet pipe of the oil cooler is inserted, whereby the engine is a vertical engine, an installation direction of a crank shaft is defined as a front-back direction, and when viewed in a direction parallel to the installation direction of the crank shaft, a horizontal direction perpendicular to the front-back direction is defined as a right-left lateral direction, the base attaching seat is provided in a lateral outer surface of a cylinder block wall, characterized in that; the seating portion of the base for component mounting is configured to seat the base attaching seat from its lateral side, and the oil cooler is attached to the oil cooler attaching seat at a lateral position of the seating portion of the base for component mounting, the base for component mounting includes an oil filter attaching seat to which the oil filter is attached from its lateral side, and the oil inlet chamber that introduces engine oil from the oil inlet of the base attaching seat to the oil cooler is provided at the seating portion configured to seat the base for component mounting on the base attaching seat and is located at a higher position than the oil filter when viewed from its lateral side. an oil gallery; a base attaching seat provided in an engine frame wall; and a base for component mounting attached to the base attaching seat; wherein the oil cooler and the oil filter are mounted on the base for component mounting, and the base attaching seat is provided with an oil inlet communicating with an upstream-side passage of the oil gallery, and an oil outlet communicating with a downstream-side passage of the oil gallery, by attaching the base for component mounting to the base attaching seat, engine oil flowing into the oil inlet of the base attaching seat from the upstream-side passage of the oil gallery passes the base for component mounting, the oil cooler, and the oil filter, and flows out of the oil outlet of the base attaching seat to the downstream-side passage of the oil gallery, the base for component mounting includes a seating portion configured to seat the base attaching seat thereon and an oil cooler attaching seat configured to attach the oil cooler thereto, the seating portion of the base for component mounting includes an oil inlet chamber connected to the oil inlet of the base attaching seat, and the oil cooler attaching seat includes an oil outlet of the oil inlet chamber into which the oil inlet pipe of the oil cooler is inserted and a reentry oil inlet into which the oil outlet pipe of the oil cooler is inserted, whereby the engine is a vertical engine, an installation direction of a crank shaft is defined as a front-back direction, and when viewed in a direction parallel to the installation direction of the crank shaft, a horizontal direction perpendicular to the front-back direction is defined as a right-left lateral direction, the base attaching seat is provided in a lateral outer surface of a cylinder block wall, characterized in that; the seating portion of the base for component mounting is configured to seat the base attaching seat from its lateral side, and the oil cooler is attached to the oil cooler attaching seat at a lateral position of the seating portion of the base for component mounting, the base for component mounting includes an oil filter attaching seat to which the oil filter is attached from its lateral side, and the oil inlet chamber that introduces engine oil from the oil inlet of the base attaching seat to the oil cooler is provided at the seating portion configured to seat the base for component mounting on the base attaching seat and is located at a higher position than the oil filter when viewed from its lateral side.