Disclosed are an apparatus and method for measuring sleep apnea based on images according to impedance data from an upper airway and a thorax of a subject, in which electrical impedance tomography (EIT) using electrodes attached to an upper airway and a thorax is used to generate an image of air distribution inside a lung according to opening and construction of an upper airway to diagnose at least one of among obstructive apnea, central apnea and complex apnea, thereby coming up with a treatment plan.