Nanopore-based sensing methods are valuable tools for solution-based single-particle analysis of many biomolecules and particles that play important roles in life and medicine, such as nucleic acids, proteins, viruses, and exosomes. The conventional nanopore method is based on direct current measurement, and the available information on particle size and zeta potential is limited. Here, we developed an alternating current-based nanopore method using lock-in measurement to overcome the longstanding and conflicting limitations of both low noise and wide bandwidth, thereby demonstrating impedance measurement of a single nanoparticle. We determined the particle size, zeta potential, and electric capacitance from the frequency responses of various particles ranging in diameter from 100 nm to several micrometers. Our nanopore method was highly accurate, identifying the type of virus with over 85% sensitivity using single-particle measurement and machine learning. This method is expected to have a variety of applications such as sensing of various nanoparticles and characterization of single nanoparticles.