The MEG experiment, designed to search for the μ → eγ decay, completed data-taking in 2013 and set an upper limit on the process ≤ 4.2 × 10−13 @ 90% C.L.. In order to increase the sensitivity reach of the experiment by an order of magnitude to the level of 6×10e−14, an upgrade,known as MEG II, which involves substantial changes to the experiment, has been undertaken.
After giving an overview of the published MEG result, I present the motivation for the upgrade and a detailed overview of the design of the experiment and commissioning status. I will also briefly discuss the comparison among MEG II and future experiments, highlighting the complementarity from theoretical and experimental points of view.