According to one embodiment, a fuser including a heating section which heats a hot-melt visualizing material fixed to a sheet medium and the sheet medium, a heat generator which increases the temperature of the heating section in accordance with supply of power, a temperature detector which detects the temperature of the heating section, and a controller which outputs temperature information during the increasing of the temperature on the basis of the temperature of the heating section detected by the temperature detector while the temperature of the heating section increases so that notification can be provided that fusing is possible for an image only using a single color hot-melt visualizing material.