The 2014 International Symposium on Electrical Insulating Materials (ISEIM) was held at Toki Messe in Niigata city, Japan, from June 1 to 5, 2014. The symposium was sponsored by the IEEJ (Institute of Electrical Engineers of Japan) Technical Committee on Dielectrics and Electrical Insulation, and technically co-sponsored by IEEE DEIS. The first ISEIM was held in Tokyo in 1995, the second in Toyohashi in 1998, the third in Himeji in 2001, the fourth in Kitakyushu in 2005, the fifth in Yokkaichi in 2008, and the sixth in Kyoto in 2011. A total of 162 participants from 16 countries attended, and a total of 155 papers appeared in the proceedings. The topics included nanotechnology, asset management, HVDC technologies, numerical simulation, etc., in line with new trends in the electricity market. Before the symposium, a workshop on APIANS (Analysis for Polymeric Insulating materials using Advanced Numerical Simulation) was held, with five invited speakers. Two invited speakers delivered special lectures to mark the opening of the symposium; Prof. Keith Nelson (Rensselaer Polytechnic Inst.), delivered the Inuishi Memorial Lecture entitled "Nanodielectrics-the First Decade and Beyond," and Prof. George Chen (Southampton University, UK) spoke on "The Missing Link-The Role of Space Charge in Polymeric Insulation Lifetime."