Imprecision　and　vagueness　often　occur　in　practical　multi-attribute　decision　making　(MADM)　problems.　Intuitionistic　fuzzy　(IF)　sets　are　flexible　to　simulate　these　situations.　The　aim　of　this　paper　is　to　develop　an　effective　method　for　solving　MADM　problems　in　which　the　attribute　values　are　expressed　with　IF　sets.　Inspired　by　TOPSIS,　we　propose　a　new　ranking　function　of　IF　sets,　which　takes　into　the　amount　and　the　reliability　of　an　IF　set.　Hereby　we　develop　a　new　MADM　method.　An　example　of　the　investment　selection　problem　is　examined　to　demonstrate　applicability　and　feasibility　of　the　proposed　method.　It　is　shown　that　the　proposed　method　has　some　advantages　over　other　methods.