A living body heating instrument is pushed or inserted into an affected part to continuously perform cauterization and vaccinotherapy. A living body heating instrument (10) that is pushed or inserted into an affected part (1) of a living body to heat the affected part (1) includes: an inner needle (11) and an outer needle (21) having a hollow portion (22) into which the inner needle (11) is inserted through an opening at the needle base side toward the needle tip side. The inner needle (11) has biocompatibility and thermal conductivity, and contains a heater (13). The affected part (1) is cauterized by the heater (13) with the inner needle (11) inserted in the outer needle (21). Next, the inner needle (11) is withdrawn, and a drug (40) is injected through the outer needle (21), which remains inserted, to perform immunotherapy. A temperature detecting element (14) may be provided in an inner part of the inner needle (11) or on an outer surface of the outer needle (21).
