Abstract : The Nemo3 detector was designed for the study of double beta decay and in particular the search for neutrinoless double beta decay ( bb0v). The quantity of 100Mo in the detector (7 kg) allows also a competitive measurement of the two-neutrino double beta decay ( bb2v) of 100Mo to the excited 0+1 state of 100Ru (eeNy channel). Monte-Carlo simulations of the effect and of all the possible sources of background have been studied in order to determine their contributions to the full Nemo3 experimental data (2003-2011). These one have then been analysed : the bb2v decay half-life has been measured, and a limit on the bb0v decay has been obtained. Moreover, the SuperNEMO experiment aims to reach a sensitivity up to 1026 years on the half-life of neutrinoless double beta decay. The SuperNEMO detector radioactivity has to be as low as possible. Especially radiopurity levels of 2 µBq.kg-1 in 208Tl and 10 µBq.kg-1 in 214Bi are required for the source foils. The gamma-spectrometry can not measure such low contamination levels. Hence, a BiPo dedicated detector has been developped to measure 208Tl and 214Bi contaminations, identi ng the Bi->Po->Pb b-alpha chains. A proof of principle has been performed and the detector background has been measured. Assuming these values, a full BiPo detector of 3:6m2 can achieve the required sensitivities for the SuperNEMO source foils within six months of measurement.