Orexin neurons in the hypothalamus regulate physiological functions, including energy homeostasis and wakefulness, and are also related to motivation. Here, we examined the roles of orexin neurons in motivated behaviors. We measured the activities of orexin neurons related to motivated behavior under the fixed ratio (FR) schedule and progressive ratio (PR) test of a touchscreen-based automated operant task using fiber photometry. We found that under FR5 conditions in which rats were able to obtain a food pellet by touching the screen consecutively five times, the orexin neuron activity peaked approximately 1.65 sec before rats obtained the reward, and then decreased after reward intake. Moreover, such changes in orexin neuron activity were　gradually increased in the PR schedule test. On the other hand, temporal and momentary optogenetic suppression of the increased orexin neuron activity inhibited the reward-seeking behavior in FR5 schedule and reduced the breakpoint in the PR test. These observations suggest that the activity of orexin neurons is associated with the amount of effort to obtain reward in motivated behaviors, and that dynamic changes in orexin neuron activity may be related to craving and reward prediction, and satisfaction.