A test apparatus is provided. The test apparatus includes: a signal provision section that provides a test signal to a device under test; an input section that inputs the output signal outputted from the device under test in response to the test signal as a signal-under-test; a periodic pulse generating section that generates a periodic pulse having a pulse width corresponding to one cycle of the signal-under-test; a converting section that outputs a voltage corresponding to the width of periodic pulse; an AD converter that converts a voltage to a digital voltage value; a pulse width calculating section that calculates a digital pulse width indicative of the width of the periodic pulse based on the digital voltage value; and an adjusting section that adjusts a conversion parameter that converts between the digital voltage value and the digital pulse width.
