An internal temperature measuring device is configured to include an acquisition unit that acquires a one side temperature and a one side heat flux of a measurement target on a one side surface side and an opposite side temperature and an opposite side heat flux of the measurement target on an opposite side surface side； and a computation unit that computes an internal temperature of the measurement target by applying the one side temperature, the one side heat flux, the opposite side temperature, and the opposite side heat flux.本發明提供一種既確保測定之簡便性或舒適性，亦能夠降低誤差影響之內部溫度之新穎之測定技術。 構成一種內部溫度測定裝置，其具備：取得部，其取得被測定體之一側面側之一側溫度、一側熱通量與上述被測定體之另一側面側之另一側溫度、上述另一側熱通量；及運算部，其使用上述一側溫度、上述一側熱通量、上述另一側溫度及上述另一側熱通量而運算上述被測定體之內部溫度。
