Electrochemical Element, Electrochemical Module, Electrochemical Device, and Energy System

An electrochemical element including a conductive plate-like support provided with an internal passage therein. The plate-like support includes, in at least a portion of a metal support included in the plate-like support: a gas-permeable portion through which gas is permeable between the internal passage, which is located inside the plate-like support, and the outside; and an electrochemical reaction portion that entirely or partially covers the gas-permeable portion and includes at least a film-like electrode layer, a film-like electrolyte layer, and a film-like counter electrode layer in the stated order. The plate-like support is provided with a plurality of passages in the internal passage.