A tappet comprising: a lash adjuster ; and a tappet body into which the lash adjuster is inserted and incorporated, wherein the lash adjuster has a plunger having a top portion on which a lower end portion of a push rod is slidable, and a body in which the plunger is housed so as to be vertically movable, and the tappet body has a lower surface portion which slidingly contacts a cam , an outer peripheral surface portion which is slidable on a tappet guide, a receiving surface portion which is located inside the outer peripheral surface portion , receives lubricating oil, and faces upward, an assembly hole which is located inside the outer peripheral surface portion , extends vertically, and has an upper end opened to the receiving surface portion and a lower end closed, and in which the body is inserted and assembled, a receiving space which is located inside the outer peripheral surface portion and opened to an upside of the receiving surface portion , and an oil guide passage which is located at the outer peripheral surface portion or between the outer peripheral surface portion and the assembly hole , and extends so as to guide the lubricating oil received by the receiving surface portion to the cam , characterized in that the oil guide passage has an oil guide groove extending vertically in the outer peripheral surface portion . a lash adjuster ; and a tappet body into which the lash adjuster is inserted and incorporated, wherein the lash adjuster has a plunger having a top portion on which a lower end portion of a push rod is slidable, and a body in which the plunger is housed so as to be vertically movable, and the tappet body has a lower surface portion which slidingly contacts a cam , an outer peripheral surface portion which is slidable on a tappet guide, a receiving surface portion which is located inside the outer peripheral surface portion , receives lubricating oil, and faces upward, an assembly hole which is located inside the outer peripheral surface portion , extends vertically, and has an upper end opened to the receiving surface portion and a lower end closed, and in which the body is inserted and assembled, a receiving space which is located inside the outer peripheral surface portion and opened to an upside of the receiving surface portion , and an oil guide passage which is located at the outer peripheral surface portion or between the outer peripheral surface portion and the assembly hole , and extends so as to guide the lubricating oil received by the receiving surface portion to the cam , a lower surface portion which slidingly contacts a cam , an outer peripheral surface portion which is slidable on a tappet guide, a receiving surface portion which is located inside the outer peripheral surface portion , receives lubricating oil, and faces upward, an assembly hole which is located inside the outer peripheral surface portion , extends vertically, and has an upper end opened to the receiving surface portion and a lower end closed, and in which the body is inserted and assembled, a receiving space which is located inside the outer peripheral surface portion and opened to an upside of the receiving surface portion , and an oil guide passage which is located at the outer peripheral surface portion or between the outer peripheral surface portion and the assembly hole , and extends so as to guide the lubricating oil received by the receiving surface portion to the cam , characterized in that the oil guide passage has an oil guide groove extending vertically in the outer peripheral surface portion . <EOS>