The invention provides a flux cored wire for joining dissimilar materials with each other, capable of enhancing a bonding strength upon joining an aluminum-base material with a steel-base material, and excellent in bonding efficiency, which is obtained by filling a bonded joint wherein a steel based member is joined with an aluminum based member for joining dissimilar materials together in the interior an aluminum alloy envelope, so that the bonded joint is formed into a fluorid containing 0.1-15 mass% of aluminum fluoride of the total mass of the flux cored wire and no chloride, and 0.3-20 mass% of the bonded joint of the total mass of the flux cored wire is filled. If such a flux cored wire is use, it is possible to obtain a high bonding strength in the case of melt weld-bonding of high-strength dissimilar materials with each other, that is, the high-strength steel member with the high-strength 6000 series aluminum alloy member.