The apparatus for assessing the risk of cerebrovascular diseases comprises a sensor part 1, a circuit part 2, a computation part 3 and an output part 4, where the circuit part 2 is a functional part for driving the sensor part 1 and transmitting a signal detected at the sensor part 1 to the computation part 3 and comprises a transmission circuit 21, a first receiving circuit 22, a second receiving circuit 23 and the like. The transmission circuit 21 is in connection with a transmission device 111 and a transmission device 121, for driving these devices to generate a continuous wave. A rate wave form computation part 31 is in connection with the first receiving circuit 22 and the second receiving circuit 23 to obtain the frequency of the reflected continuous wave as detected with the receiving units 112 and 122. Comparing the frequency with the frequency from the transmission circuit 21, the variation of the frequency is detected. Based on these values, blood flow rate “v” can be determined. In such manner, an apparatus for assessing the risk of cerebrovascular diseases with fewer burdens to persons to be examined and with simple measurement units can be provided.