Measurement device and image forming apparatus

A measurement device comprising:

• a detector configured to detect an ultrasonic wave transmitted through a measurement target;
• a driving circuit configured to drive the detector;
• a processing circuit configured to:
• measure a basis weight of a measurement target by causing the measurement target to vibrate through an application of the ultrasonic wave, measure a strength of the ultrasonic wave detected by the detector, and calculate the basis weight of the measurement target on a basis of a measured value of the strength of the ultrasonic wave from a correlation data indicating a correlation between the measured value and the basis weight, the driving circuit including a first mode that measures the basis weight using a first burst wave sensitive in a first predetermined range of basis weight values and a second mode that measures the basis weight using a second burst wave sensitive in a second range of basis weight values different from the first range;
• and
• a control circuit that controls the driving circuit to execute at least one of the first mode and the second mode, wherein
• the control circuit controls the driving circuit to execute the second mode, and if the basis weight measured by the second mode is not included in the second range, the control circuit controls the driving circuit to execute the first mode after stopping the application of the ultrasonic wave.