Last year, the country saw 3,397 cases, a dramatic 13-fold jump from just 255 in 2020, the Asahi newspaper reported, citing the National Police Agency (NPA).
The number has doubled annually since 2020, rising from 442 in 2021 to 819 in 2022 and 1,717 in 2023, according to NPA data.
Ibaraki prefecture, northeast of Tokyo, reported the highest number of stolen outdoor air-conditioning units last year with 594 cases, followed closely by Saitama at 563 and Chiba at 402.
In comparison, metropolitan cities such as Tokyo and Osaka saw only 60 and 101 theft cases, respectively, which police said meant that thieves tended to avoid urban areas given the higher risk of detection.
According to the NPA, rising copper prices could have fuelled the surge in crimes, as outdoor air-conditioning units often have copper pipes.
