Observed tiny neutrino masses may indicate the existence of new physics including a source of Lepton Number Violation (LNV) at high energies. The effect of such a high-scale physics may be well described by higher dimensional LNV operators. We investigated the dimension-five lepton number violating operator, ℓ±ℓ'±W∓W∓, containing important information on the origin of tiny neutrino masses, which is independent of that from Weinberg operator, and we found that this operator can be probed by current and future experiments, such as neutrinoless double beta decay and high-energy collider experiments. In this talk, I'll show our result and discuss the constraint on the scale of new physics from these experiments. This talk is based on the paper, M. Aoki, K. Enomoto, S. Kanemura, Phys. Rev. D101, 115019 (arXiv:2002.12265[hep-ph]).