To obtain a heat adhesive composite fiber capable of adhering to a highly water-absorbing resin strongly by mixing with the highly water- absorbing resin and performing a heat-treatment for preventing it from falling off, and to provide a formed article by using the same fiber.

This heat adhesive composite fiber used together with a highly water-absorbing resin powder or highly water-absorbing resin comprises a low melting component constituted of mixture consisting of 30-100 wt.% ethylene- vinyl acetate copolymer consisting of 5-40 wt.% vinyl acetate with 60-95 wt.% ethylene or its saponified material as a component A, and 0-70 wt.% polyethylene as a component B, and a high melting component having a higher melting point by ≥15°C than that of the low melting component, and is characterized in that the low melting component forms at least a part of the heat adhesive composite fiber surface continuously in its length direction and the heat adhesive composite fiber has 0.5-50 denier single fiber fineness.