A thermal image sensor (11) and an air conditioner (1) that can carry out high-accuracy human detection without having to increase the memory capacity and to improve the CPU's ability are provided. The thermal image sensor (11) and the air conditioner (1) are characterized in that temperature data of significant pixels selected from all the pixels in the immediately preceding step are acquired by a thinning scanner (120), a human probability for each of the significant pixels is generated by a human probability generator (130), weight values for all the pixels are generated from the human probabilities for the significant pixels by a pixel weight calculator (140), and pixels having a larger weight value are selected, as the significant pixels to be used in the next step, by an all-pixel sorter (150), thereby assigning a larger number of pixels to a region in which there is a high probability that a person is existing while the number of significant pixels used in total is kept constant.