Provided are an inner part and a resin molded article according to which it is possible to mitigate the concentration of stress at a distal end of a melt rib. An inner part, around which an outer portion is to be arranged through integral molding, includes a main body portion made of resin, and a melt rib provided protruding outward from the main body portion. The melt rib is formed such that a height of the melt rib is greater than a thickness of the melt rib, the thickness decreases from the main body portion to a distal end of the melt rib, and the melt rib includes a melting portion configured to partially melt during molding of the outer portion.