An electrochemical element including a plate-like support provided with an internal passage therein. The plate-like support includes a gas-permeable portion through which gas is permeable between the internal passage and the outside of the plate-like support and an electrochemical reaction portion that is formed by stacking at least a film-like electrode layer, a film-like electrolyte layer, and a film-like counter electrode layer in the stated order in a predetermined stacking direction on an outer face of the plate-like support so as to entirely or partially cover the gas-permeable portion. A first gas, that is one of reducing component gas and oxidative component gas, flows through the internal passage, and the internal passage is provided with a turbulence forming body that forms a turbulence state of the first gas.