To provide a thermal protector, capable of preventing the deterioration of spring properties of a movable plate under high temperatures and maintaining contact pressure force of a contact even under the high temperatures, and also capable of preventing the decrease of operating temperature while suppressing internal resistance low.

The thermal protector includes a movable plate 30 that is mounted with a movable contact 32 to one end and a terminal 13 to the end on the opposite side, a by-pass member 40 that is joined with the movable plate at the end on which the movable contact of this movable plate is mounted and the end on which the terminal is mounted, and a bi-metal element 20 that moves the movable contact of the movable plate by snap-action to carry out opening and closing of an electrical circuit. The by-pass member is composed of a different metal material having a higher conductivity than the metal material constituting the movable plate, and the movable plate and the by-pass member are heat-treated after joining, and the metal material of the movable plate is precipitation-cured while softening is carried out with the metal material of the by-pass member.