A new compound Er3Co4Al12 was prepared by arc melting under argon atmosphere. The powder X-ray diffraction data of Er3Co4Al12 were successfully indexed, giving a hexagonal structure with a = 8.6185(2) Å, c = 9.2347(3) Å, and unit-cell volume V = 594.04 Å3. Compound Er3Co4Al12 has the Gd3Ru4Al12 type-structure, Z = 2 and space group P63/mmc.