PURPOSE: To efficiently warm the local part in the body by using a shape memory alloy wire becoming an elongated linear shape at temp. lower than bodily temp. or a spiral becoming an elongated linear shape within an elastic limit as a warming element and introducing the same into the local part in the body by a puncture needle.

CONSTITUTION: A warming element 1 becomes a linear shape or gently curved linear shape at temp. lower than bodily tempe. When the warming element 1 is warmed to bodily temp. or more, said element 1 is deformed into a spiral shape or folded wire shape. When the warming element 1 is introduced into the local part in the body, a puncture needle is allowed to reach the malignant tumor part in the body under fluoroscopy and the warming element is passed through the puncture needle. By allowing a physiological saline solution having temp. lower than bodily temp. if necessary, the deformation of the warming element can be prevented. When the warming element is passed through the puncture needle to reach the local part in the body, the warming element reaches temp. equal to or more than bodily tempe. and deformed into the shape to which memory processing is applied, that is, the spiral shape or folded wire shape. The puncture needle is pulled out and a high frequency magnetic field is applied to the heating element externally. An induced current flows to the heating element becoming the spiral shape or folded wire shape and the temp. of the heating element is raised by Joule heat to heat the tumor part.