Disclosed is a fuel supply pump including a tappet structure body having a roller that contacts a cam and a tappet body disposed with a roller housing portion in which the roller is housed, with a pressure adjusting member for dispersing load force being interposed between the tappet body and a plunger. The pressure adjusting member includes a concave portion in a center portion of a surface that faces the tappet body and contacts the tappet body at the peripheral portion of the concave portion.