A breathing simulator for use in an evaluation test of respirators is provided, the breathing simulator being able to simulate larger respirations, undergoing a change neither in cycle nor in the amount of ventilation even in a test of respirators having a high pressure drop, able to easily generate not only such regular waveforms as a sine wave, a rectangular wave and a triangular wave but also respiration waveforms of workers and arbitrarily created waveforms as air waveforms, being reduced in size and power consumption, and easy to maintenance. The breathing simulator comprises plural air cylinders (1) for generating an air waveform, a single electric cylinder (2) for actuating the air cylinders, a servo controller (3) for controlling the operation of the electric cylinder, an input/output unit (4) for recording an analog input from the exterior and reproducing the recorded data at an arbitrary magnification, a PC (5) for creating an arbitrary waveform, and a waveform generator 6 for outputting the created waveform.