A medium heating device includes a support portion configured to support a medium being transported, a heating unit configured to heat a medium supported by the support portion, and a detector configured to detect a temperature of the support portion. The support portion includes a metal plate including a first surface as the support face, an end portion of the metal plate is bent toward an opposite side to the first surface, the metal plate is fixed by a fixing portion and a fixing portion next to the fixing portion in a width direction, and a detection position of the detector is set to a position between the mutually adjacent fixing portions in the width direction.