Recent development in the study of the structure of light Λ and double Λ hypernuclei is reviewed from the view point of few-body problems and interactions between the constituent particles. In the study the present author and collaborators employed Gaussian expansion method for few-body calculations; the method has been applied to many kinds of few-body systems in the fields of nuclear physics and exotic atomic/molecular physics. We reviewed the following subjects studied using the method: (1) Precise three- and four-body calculations of 7 Λ He, 7 Λ Li, 7 Λ Be, 8 Λ Li, 8 Λ Be, 9 Λ Be, 10 Λ Be, 10 Λ B and 13 Λ C provide important information on the spin structure of the underlying ΛN interaction by comparing the calculated results with the recent experimental data by γ-ray hypernuclear spectroscopy. (2) The Λ-Σ coupling effect was investigated in 4 Λ H and 4 Λ He on the basis of the N + N + N + Λ (Σ) four-body model. (3) A systematic study of double-Λ hypernuclei and the ΛΛ interaction, based on the NAGARA event data (6 ΛΛ He), was performed within the α + x + Λ + Λ cluster model (x = n, p, d, t,3He and α) and α + α + n + Λ + Λ cluster model, (4) The Demachi-Yanagi event was interpreted as observation of the 2+ state of 10 ΛΛ Be, (5) The Hida event was interpreted as observation of the ground state of 11 ΛΛ Be.