A compression ignition engine, comprising: a combustion chamber formed by a cylinder, a ceiling surface of a cylinder head and a crown surface of a piston; a fuel injector provided at a central portion, in a radial direction, of the ceiling surface of the cylinder along a cylinder axis and including plural injection holes (31, 41) to inject fuel into the combustion chamber; and a cavity provided at the crown surface of the piston, wherein the cavity includes a first cavity section which is provided in a central area, in the radial direction, of the crown surface and has a first bottom portion having a first depth, in a direction of the cylinder axis, from the crown surface, a second cavity section which is provided outside the first cavity section and has a second bottom portion having a second depth, in the direction of the cylinder axis, from the crown surface, the second depth being shallower than the first depth, and a lip which is provided to connect the first cavity section and the second cavity section, the plural injection holes (31, 41) of the fuel injector include a first injection-hole group in which plural first injection holes are provided circumferentially and a second injection-hole group in which plural second injection holes are provided circumferentially, the first injection-hole group and the second injection-hole group are configured to inject the fuel toward the lip concurrently, and the plural second injection holes are directed toward a part closer to the ceiling surface in the cylinder-axis direction than a part to which the plural first injection holes are directed, characterized in that the lip has a convex-shaped curved surface with a specified radius which extends from a lower-end portion to an upper-end portion, in the second cavity section, a part extending from the second bottom portion to an upper-end part of a rising wall area is formed by a nearly 1/4 circle having a first radius, and the upper-end part of the rising wall area is continuous to a lower-end position of an upper-end portion which is formed by a nearly 1/4 circle having a second radius, in the radial direction, a distance (Sh) between a central point of the first radius and a central point of the second radius is equal to or greater than a sum of the first radius and the second radius, and an upper end of the second upper-end portion of the second cavity section is continuous to the squish area of the piston. a combustion chamber formed by a cylinder, a ceiling surface of a cylinder head and a crown surface of a piston; a fuel injector provided at a central portion, in a radial direction, of the ceiling surface of the cylinder along a cylinder axis and including plural injection holes (31, 41) to inject fuel into the combustion chamber; and a cavity provided at the crown surface of the piston, wherein the cavity includes a first cavity section which is provided in a central area, in the radial direction, of the crown surface and has a first bottom portion having a first depth, in a direction of the cylinder axis, from the crown surface, a second cavity section which is provided outside the first cavity section and has a second bottom portion having a second depth, in the direction of the cylinder axis, from the crown surface, the second depth being shallower than the first depth, and a lip which is provided to connect the first cavity section and the second cavity section, the plural injection holes (31, 41) of the fuel injector include a first injection-hole group in which plural first injection holes are provided circumferentially and a second injection-hole group in which plural second injection holes are provided circumferentially, the first injection-hole group and the second injection-hole group are configured to inject the fuel toward the lip concurrently, and the plural second injection holes are directed toward a part closer to the ceiling surface in the cylinder-axis direction than a part to which the plural first injection holes are directed, characterized in that the lip has a convex-shaped curved surface with a specified radius which extends from a lower-end portion to an upper-end portion, in the second cavity section, a part extending from the second bottom portion to an upper-end part of a rising wall area is formed by a nearly 1/4 circle having a first radius, and the upper-end part of the rising wall area is continuous to a lower-end position of an upper-end portion which is formed by a nearly 1/4 circle having a second radius, in the radial direction, a distance (Sh) between a central point of the first radius and a central point of the second radius is equal to or greater than a sum of the first radius and the second radius, and an upper end of the second upper-end portion of the second cavity section is continuous to the squish area of the piston.