Provided are an anode active material for lithium ion rechargeable batteries and an anode, which are capable, when used in a lithium ion rechargeable battery, of providing excellent charge/discharge capacity and cycle characteristics, and also high rate performance, as well as a lithium ion rechargeable battery using the same. The anode active material contains particles having a crystal phase represented by RAx, wherein R is at least one element selected from the group consisting of rare earth elements including Sc and Y but excluding La, A is Si and/or Ge, and x satisfies 1.0≦x≦2.0, and a crystal phase consisting of A. The material is thus useful as an anode material for lithium ion rechargeable batteries.