A modified expanded bead that includes an expanded bead which includes a specific base polymer (β) and a coating layer which includes a specific base polymer (α). The coating layer covers at least part of an outer surface of the expanded bead. The melting point Tα of the base polymer (α) and the melting point Tβ of the base polymer (β) satisfy a relationship of 0≤Tα−Tβ≤20. When the modified expanded bead is cut into two halves along a cutting plane to form two half portions and thereafter one of the two half portions is cut along planes perpendicular to the cutting plane to form ten small pieces, outermost pieces among the ten small pieces have a xylene-insoluble content (B) which is less than a xylene-insoluble content (A) in the half portion and the xylene-insoluble content (A) is 10-80% by mass.