A vascular viscoelasticity evaluation device comprising: - a cuff and pressure application means to exert an external force substantially the same as or greater than systolic blood pressure on a blood vessel; - a pulse wave component extraction means for extracting a pulse wave component of cuff pressure; - a differential waveform formation means for subjecting the extracted pulse wave component to temporal differentiation to calculate a primary differential value and form a differential waveform; - a positive first amplitude peak value detecting means for detecting a positive amplitude peak value that occurs first within one pulse wave of a differential waveform obtained by the temporal differentiation of a pulse wave component extracted in a state in which the external force has been exerted; wherein the device additionally comprises: - a negative second amplitude peak value detecting means for detecting a plurality of negative amplitude peak values that occur in the pulse wave in which the positive amplitude peak value that occurs first was detected and for determining a negative amplitude peak value that occurs second among the plurality of negative amplitude peak values; - a calculation means for calculating a ratio of the positive amplitude peak value that occurs first to the negative amplitude peak value that occurs second among the plurality of negative amplitude peak values, or for calculating a difference between the positive amplitude peak value that occurs first and the negative amplitude peak value that occurs second among the plurality of negative amplitude peak values; and - a vascular viscoelasticity evaluation means for evaluating vascular viscoelasticity on a basis of the ratio calculated by the calculation means or on a basis of the difference calculated by the calculation means. - a cuff and pressure application means to exert an external force substantially the same as or greater than systolic blood pressure on a blood vessel; - a pulse wave component extraction means for extracting a pulse wave component of cuff pressure; - a differential waveform formation means for subjecting the extracted pulse wave component to temporal differentiation to calculate a primary differential value and form a differential waveform; - a positive first amplitude peak value detecting means for detecting a positive amplitude peak value that occurs first within one pulse wave of a differential waveform obtained by the temporal differentiation of a pulse wave component extracted in a state in which the external force has been exerted; - a negative second amplitude peak value detecting means for detecting a plurality of negative amplitude peak values that occur in the pulse wave in which the positive amplitude peak value that occurs first was detected and for determining a negative amplitude peak value that occurs second among the plurality of negative amplitude peak values; - a calculation means for calculating a ratio of the positive amplitude peak value that occurs first to the negative amplitude peak value that occurs second among the plurality of negative amplitude peak values, or for calculating a difference between the positive amplitude peak value that occurs first and the negative amplitude peak value that occurs second among the plurality of negative amplitude peak values; and - a vascular viscoelasticity evaluation means for evaluating vascular viscoelasticity on a basis of the ratio calculated by the calculation means or on a basis of the difference calculated by the calculation means.