We have developed the electrochemical porosimetry analyzing microstructures of porous electrodes, which can give geometric information most meaningful in electrochemical systems. The methodology is based on the transmission line model with pore size distribution (TLM-PSD) that relates electrochemical impedance data with microstructural information. Pore length (lp), as well as pore size distribution, can be obtained by fitting the TLM-PSD to the experimental impedance data of a porous electrode. This geometric information was validated for the microporous, mesoporous and macroporous samples by comparing with the data obtained from conventional porosimetry. It was also shown that the electrochemical porosimetry could be used as a nondestructive probe to investigate the construction of electrochemical devices.