The present invention estimates simply and accurately transdermal water loss, and further provides an apparatus for evaluating the barrier function of the skin on the basis of this. The apparatus includes a main body portion 10, and the application electrode 12 capable of applying a plurality of alternating voltages to be installed in the main body, the detection electrodes 13 for detecting susceptance installed in the main body, admittance, or any of the conductance If a display unit 14 which is installed in the main body is built in the main body portion, the detected susceptance, admittance, or operations for calculating the characteristic value P can be an estimate of the transdermal water loss on the basis of either the conductance and a unit estimates the percutaneous water transpiration amount based on the calculated characteristic value P, to evaluate the skin barrier function based on this. .BACKGROUND【課題】簡便かつ的確に経皮水分蒸散量を推定し、さらにこれに基づいて皮膚のバリア機能を評価する装置を提供する。【解決手段】本体部10と、本体部に設置される複数の交流電圧を印加し得る印加電極12と、前記本体部に設置されるサセプタンス、アドミタンス、又はコンダクタンスのいずれかを検出する検出電極13と、本体部に設置される表示部14と、本体部に内蔵され、検出したサセプタンス、アドミタンス、又はコンダクタンスのいずれかに基づいて経皮水分蒸散量の推定値となりえる特性値Pを算出する演算部とを備え、算出された特性値Pに基づいて経皮水分蒸散量を推定し、これに基づいて皮膚バリア機能を評価する。【選択図】図1