Time-saving (time-efficient) goods and services are increasingly developed and diffused. Such goods and services increase the disposable time for households, and the time saved may be allocated to other activities consuming energy/electricity. The present study sets a simple theoretical model and shows a mechanism, called the time rebound effect, with which time-saving goods increase energy consumption through household behaviors. Furthermore, we reveal empirical evidence for this model by conducting a Japanese household survey. In particular, our analysis shows that the time rebound effect occurs on using the dishwasher, clothes dryer, or a net ordering/delivery service. However, its impact is very small: the extra electricity usage is about 1.4% of the daily usage at most.