The invention is a heating device (1) that comprises a heating element (10) that generates heat by means of an electric current, and a current control module (20) that controls the current so that the resistance value of said heating element (10) (RGP) matches a target resistance value (RTRG). Said heating device (1) integrally houses the current control module (20) in a substantially tubular housing (30), and the current control module (20) is provided with: a reference resistance value storage means (232) that stores a resistance value at a specified target temperature (TTRG) as a reference resistance value (RC); a resistance value change application means (233) that, if the resistance value (RGP) of the heating element (10) when current is flowing is below the reference resistance value (RC), maintains the current, and if the reference resistance value (RC) is exceeded, shuts off the current and applies a resistance value change accompanying a temperature change of the heating element (10) to current control; and a deterioration assessment means (234) that assesses deterioration by assessing as a power threshold value (PREF), a deterioration-time power value (PWRN) computed by multiplying an initial power value (PINT) by a specified ratio.