Effects of ambient and body temperature on the circadian locomotive rhythms of the honeybee have been investigated using foragers of Apis cerana japonica. (1) Temperature compensation-The honeybees were kept at 27degreeC(dC), and 35(dC) in DD and LL condition, and the free-running periods were examined. Q10 which was calculated by tau—values was estimated to be 0.88 in DD and 0.99 in LL condition, respectively, indicating that temperature compensation is achieved in the circadian locomotive rhythm of the honeybee as well as in other insect species. (2) Entrainment to 24h-temperature cycle-10 dC amplitude temperature cycles (12h, 35 dC thermophase; 12h, 25 dC cryophase) in DD condition entrained the honeybee foragers. Following subsequent transfer to constant temperature condition (35 dC or 25 dC) produced free-running rhythm with tau of 24.7 hr at 35 dC and tau of 23.2 hr at 25 dC, respectively. The activity offset in the free-running rhythm begun from the phase of the offset at the end of entrainment of temperature cycle. On the other hand 5 dC amplitude cycles could not entrain the honeybee activity rhythm. (3) Body temperature and locomotive rhythm-During the scotophase of LD 12:12 photoperiodic regime the body (thorax and head) temperature remained at the ambient level (28 dC), but during photophase, when the foragers performed the locomotive activity, it raised up to about 34-35 dC from the light-on transition until the end of the photophase. The change of body temperature showed circadian rhythm associated with the locomotive activity. These pieces of evidence suggest that external and internal thermal condition of the honeybees regulate their circadian clock, though they are thought to live at rather constant temperature environment.