PROBLEM TO BE SOLVED: To provide an exercise intensity estimation device in which exercise intensity can be estimated with high accuracy in a situation where multiple motion including the motion of small movement may be generated in a construction worker, etc.SOLUTION: An exercise intensity estimation device previously stores exercise intensity, a heart rate and acceleration DB12c where the exercise intensity PA, the heart rate HR and 3-axial acceleration (AccX, AccY, AccZ) are associated with each other according to each of multiple types of motion of a subject. In an estimation method (1), the heart rate HR' of the estimated subject is measured by an electrocardiographic sensor and is input, and the heart rate HR and the exercise intensity PA corresponding to the heart rate HR' of the estimated subject being input from the DB12c are selected and extracted. Then, parameters β, βshowing the relationship between the heart rate HR and the exercise intensity PA extracted from the DB12c are calculated, and the exercise intensity PAe of the estimated subject is subjected to the regression analysis and is calculated based on the heart rate HR' of the estimated subject being input and the calculated parameters β, β.SELECTED DRAWING: Figure 6
