A half plain bearing that has a positioning member with a novel construction, and a manufacturing method of the half plain bearing are proposed. If part of a material from which a bearing body 13 is formed is allowed to escape to outside of a tool with a narrow width when pressed by the tool, an amount of protrusion needed for a positioning member 20 to perform a function thereof (an amount of protrusion from an outer peripheral face of the bearing body) can be ensured while suppressing an amount of deformation of the material from which the bearing body 13 is formed in a circumferential direction thereof. The positioning member 20 of the half plain bearing thus formed has a flat portion 21a and a protrusion portion 22. A tip of the protrusion portion 22 is located on a mating face side with respect to a virtual plane that includes the flat portion 21a.