A breathing exerciser includes: a guide unit for guiding an exercise pattern of breathing to a user; a breathing sensor for detecting breathing of the user; a breathing index calculating unit for calculating, based on a signal from the breathing sensor, a breathing index at least one of before and after an exercise period during which the exercise pattern is guided, the breathing index representing a characteristic of a breathing state of the user; and an outcome index calculating unit for calculating an outcome index based on at least two breathing indices, the outcome index representing an outcome of breathing exercise; and an informing unit for informing the outcome index to the user.