An angle measurement device includes: a slit through which an ion beam is incident, and a width direction of which is orthogonal to a beam traveling direction of the ion beam toward a wafer; and a plurality of electrode bodies which are provided at positions away from the slit in the beam traveling direction, and each of which includes a beam measurement surface that is a region which is exposed to the ion beam having passed through the slit. The plurality of electrode bodies are disposed such that the beam measurement surfaces of the electrode bodies are arranged in order in the width direction of the slit and the beam measurement surfaces adjacent to each other in the width direction of the slit deviate from each other in the beam traveling direction.