To improve the adhesiveness of a sealing face by first and second cover fastening bolts even if there is a difference in level between first and second components and a timing chain cover, secure the good sealability of the timing chain cover and eliminate the necessity of tolerance control for minimizing the difference in level.

In an engine comprising at least two, first and second, components 4 and 6, a first mating face 12 for the second component 6 is provided in the first component 4, and a second mating face 14 for the first component 4 is provided in the second component 6, and a first seat face 18 for a first cover tightening bolt in the side of the first component 4 and a second seat face 22 for a second cover fastening bolt in the side of the second component 6 are provided at positions near the first and second mating faces of a timing chain cover 10, and the first and second distances L1 and L2 from the centers of the first and second seat faces to the first and second mating faces are set to values of four times or less as long as the value of the diameters of the first and second cover fastening bolts, connecting the first and second seat faces through a connection member.