A method for manufacturing a blood pressure information measurement apparatus includes the following steps: forming a hole in a flexible resin sheet; inserting a connecting pipe into the hole; overlaying a first end portion and a second end portion of the flexible resin sheet such that an inner side of the first end portion contacts an outer side of the second portion; welding a location at which the first end portion and the second end portion overlap to form a first welded portion, such that the flexible resin sheet forms a tube-shaped body having a first end and a second end; flattening the tube-shaped body; welding the first end and the second to form two second welded portions, such that the tube-shaped body forms a bladder having two long sides and two short sides; and welding portions of the resin sheet which overlap along a first long side to form one or more partial welded portions.