Many　dielectrics　exhibit　a　(polarization)　relaxation　response　when　a　time-varying　electric　field　is　applied.　In　some　frequency　bands,　the　amplitude　of　the　polarization　changes　rapidly,　with　a　significant　dielectric　loss;　the　maxima　in　the　change　rate　are　referred　to　as　relaxation　peaks.　ZnO　varistors　exhibit　a　dielectric　response　with　several　relaxation　peaks,　but　the　relationship　between　the　relaxation　peaks　and　electrical　properties　has　not　been　established.　To　understand　this　relationship,　dielectric　spectroscopy　measurements　of　ZnO　varistors　were　conducted　in　the　temperature　range　of　-110　°C　to　200　°C　in　the　frequency　range　of　10-1-106　Hz.　By　changing　two　important　dopants　of　Bi2O3　and　Sb2O3,　four　relaxation　peaks,　named　Peak　A,　Peak　B,　Peak　C,　and　Peak　D,　were　detected.　It　was　found　that　peaks　A,　B,　and　D　are　indispensable　for　higher　nonlinearity　and　lower　leakage　current　density.　The　detection　of　all　four　peaks　implies　that　ZnO　varistors　possess　excellent　electrical　properties,　that　is,　a　high　breakdown　field　(235.2　V　mm-1),　nonlinear　coefficient　(76.2),　and　low　leakage　current　density　(0.065　μA　cm-2).　©　2021　The　Japan　Society　of　Applied　Physics.