An ultrasonography apparatus comprising: at least one processor, wherein the processor is configured to: acquire an ultrasound image of an arm of a subject captured by an ultrasound probe, acquire, from a detector configured to detect a posture of a palm of the subject: information representing a posture of the palm at a first time point as a first detection result, and information representing a posture of the palm at a second time point, which is after the first time point and is a time point during capturing of the ultrasound image, as a second detection result, derive a difference between the posture of the palm at the first time point and the posture of the palm at the second time point based on the first detection result and the second detection result, and perform notification in a case in which the derived difference is equal to or greater than a threshold value, characterised in that the processor is configured to add information representing a warning to the ultrasound image captured at the second time point in a case in which the derived difference is equal to or greater than the threshold value. at least one processor, wherein the processor is configured to: acquire an ultrasound image of an arm of a subject captured by an ultrasound probe, acquire, from a detector configured to detect a posture of a palm of the subject: information representing a posture of the palm at a first time point as a first detection result, and information representing a posture of the palm at a second time point, which is after the first time point and is a time point during capturing of the ultrasound image, as a second detection result, derive a difference between the posture of the palm at the first time point and the posture of the palm at the second time point based on the first detection result and the second detection result, and perform notification in a case in which the derived difference is equal to or greater than a threshold value, characterised in that the processor is configured to add information representing a warning to the ultrasound image captured at the second time point in a case in which the derived difference is equal to or greater than the threshold value. acquire an ultrasound image of an arm of a subject captured by an ultrasound probe, acquire, from a detector configured to detect a posture of a palm of the subject: information representing a posture of the palm at a first time point as a first detection result, and information representing a posture of the palm at a second time point, which is after the first time point and is a time point during capturing of the ultrasound image, as a second detection result, derive a difference between the posture of the palm at the first time point and the posture of the palm at the second time point based on the first detection result and the second detection result, and perform notification in a case in which the derived difference is equal to or greater than a threshold value, characterised in that the processor is configured to add information representing a warning to the ultrasound image captured at the second time point in a case in which the derived difference is equal to or greater than the threshold value. information representing a posture of the palm at a first time point as a first detection result, and information representing a posture of the palm at a second time point, which is after the first time point and is a time point during capturing of the ultrasound image, as a second detection result, derive a difference between the posture of the palm at the first time point and the posture of the palm at the second time point based on the first detection result and the second detection result, and perform notification in a case in which the derived difference is equal to or greater than a threshold value, characterised in that the processor is configured to add information representing a warning to the ultrasound image captured at the second time point in a case in which the derived difference is equal to or greater than the threshold value.