A woman's undergarment (A) with cup sections, comprising: a pair of left and right brassiere cups each adapted to receive a breast (B) and having a lower edge , a side edge , and an upper edge , the lower edge being downwardly curved, the side edge rising from an underarm-side end (P1) of the lower edge toward the upper edge , the upper edge extending from a sternum-side end (P2) of the lower edge to an upper end (P3) of the side edge ; cup cover pieces each disposed to cover an outer surface of the brassiere cup and separated from the outer surface of the brassiere cup , wherein the lower edge of the brassiere cup extending from the underarm-side end (P1) to the sternum-side end (P2) is sewn to a lower edge of the cup cover piece , and the side edge and the upper edge of the brassiere cup are detached from the cup cover piece ; a support panel to which the lower edges of the brassiere cups and the lower edges of the cup cover pieces are sewn together; back pieces extending from left and right sides of the support panel and adapted to cover a back of a wearer; straps each extending from the cup cover piece to the back piece ; characterised in that it further includes lift-up pieces each disposed between the brassiere cup and the cup cover piece , having a lower edge that is sewn to the lower edge of the brassiere cup and an upper end edge that is connected to the strap , and thereby configured to lift the brassiere cup from below, wherein the brassiere cup has an opening in a corner region including the upper end (P3), the lift-up piece includes an insertion portion having a strip shape extending toward the upper end edge , and the insertion portion is inserted through the opening in the corner region of the brassiere cup from the outer surface to an inner surface of the brassiere cup . a pair of left and right brassiere cups each adapted to receive a breast (B) and having a lower edge , a side edge , and an upper edge , the lower edge being downwardly curved, the side edge rising from an underarm-side end (P1) of the lower edge toward the upper edge , the upper edge extending from a sternum-side end (P2) of the lower edge to an upper end (P3) of the side edge ; cup cover pieces each disposed to cover an outer surface of the brassiere cup and separated from the outer surface of the brassiere cup , wherein the lower edge of the brassiere cup extending from the underarm-side end (P1) to the sternum-side end (P2) is sewn to a lower edge of the cup cover piece , and the side edge and the upper edge of the brassiere cup are detached from the cup cover piece ; a support panel to which the lower edges of the brassiere cups and the lower edges of the cup cover pieces are sewn together; back pieces extending from left and right sides of the support panel and adapted to cover a back of a wearer; straps each extending from the cup cover piece to the back piece ; characterised in that it further includes lift-up pieces each disposed between the brassiere cup and the cup cover piece , having a lower edge that is sewn to the lower edge of the brassiere cup and an upper end edge that is connected to the strap , and thereby configured to lift the brassiere cup from below, wherein the brassiere cup has an opening in a corner region including the upper end (P3), the lift-up piece includes an insertion portion having a strip shape extending toward the upper end edge , and the insertion portion is inserted through the opening in the corner region of the brassiere cup from the outer surface to an inner surface of the brassiere cup . <EOS>