The autogenous shrinkage and electrical characteristics of cement pastes and mortars incorporating carbon nanotube (CNT) and carbon fiber (CF) were investigated in this study. The dispersion agents for the CNT and CF were polycarboxylate-type superplasticizer and silica fume, respectively. The electrical characteristics of the pastes and mortars were investigated by means of the two-probe method, while the autogenous shrinkage characteristics of the cement pastes and mortars were discussed in the light of the reaction characteristics of cement particles. The effects of the replacement ratio of the CF to CNT, the length of CF, and the fine aggregate content on the autogenous shrinkage and electrical characteristics of the cement pastes and mortars were examined. The test results showed that the CNT addition inhibited the hydration reaction at an early stage of curing, thereby reducing the autogenous shrinkage of the pastes and mortars. The addition of CF mitigated an adverse effect of the addition of fine aggregates on the electrical resistivity of the mortars. (C) 2018 Elsevier Ltd. All rights reserved.