The relation between the bound states of light double hyper nuclei with mass number 3, 4, 5, 6 and the Λ-Λ interaction is analysed by a simple variational method. It is strongly indicated that (i) unless the Λ-Λ force is very strong ΛΛH3 and ΛΛn3 do not exist because the N-Λ force is too weak in these systems, and that (ii) the well-depth parameter of the Λ-Λ interaction must be ≳0.8 to allow the bound state ΛΛH4. These conclusions have been obtained on the assumption of a central Λ-Λ interaction of a Yukawa shape with range parameter (2mπ)−1 (mπ: π-meson mass).