Abstract: A settling time acquisition method includes writing at least one reference pattern formed by at least one shot of a charged particle beam, writing an evaluation pattern, which has been formed by combination of the first and second shots of a charged particle beam shaped to first and second patterns of different sizes and whose width size is the same as that of the reference pattern, while changing, concerning beam shaping of the second shot, a settling time of a DAC amplifier, wherein writing is performed for each settling time, measuring the width size of the reference pattern, measuring the width size of the evaluation pattern for each settling time, calculating, for each settling time, a difference between the width sizes of the reference and evaluation patterns, and acquiring a settling time from each settling time of the DAC amplifier when the difference is not exceeding a threshold value.