A speed measuring device comprising: an optical coherence tomography device that is designed to divide light, emitted from a light source, into reference light and measuring light to emit the measuring light to irradiation points, which are different from each other, on a surface of a sample including a blood vessel, and to obtain a tomographic image of the sample based on one or more interference signal(s) in which one or more reflected light(s), obtained from the measuring light reflected on the sample, and the reference light are interfering; a motion contrast calculator (S40, S70) that is designed to continuously calculate one or more first motion contrast(s) and one or more second motion contrast(s), among the irradiation points, one irradiation point disposed on the blood vessel being defined as a first irradiation point, and another irradiation point disposed on the blood vessel, that passes through the first irradiation point, and being different from the first irradiation point being defined as a second irradiation point, and the one or more first motion contrast(s) being one or more motion contrast(s) calculated based on the one or more interference signal(s) at the first irradiation point, and the one or more second motion contrast(s) being the one or more motion contrast(s) calculated based on the one or more interference signal(s) at the second irradiation point; a waveform creator that is designed to create, based on a calculation result obtained by the motion contrast calculator (S40, S70), a first motion contrast waveform, indicating chronological change in the one or more first motion contrast(s), and a second motion contrast waveform, indicating a chronological change in the one or more second motion contrast(s); a time lag calculator (S100, S110) that is designed to calculate time lag that is temporal lag between the first motion contrast waveform and the second motion contrast waveform created by the waveform creator; a distance calculator that is designed to calculate a blood vessel distance along the blood vessel from the first irradiation point to the second irradiation point; and a speed calculator that is designed to calculate, based on the time lag calculated by the time lag calculator (S100, S110) and the blood vessel distance calculated by the distance calculator, pulse wave velocity that is velocity of a pulse wave transmitted inside the blood vessel. an optical coherence tomography device that is designed to divide light, emitted from a light source, into reference light and measuring light to emit the measuring light to irradiation points, which are different from each other, on a surface of a sample including a blood vessel, and to obtain a tomographic image of the sample based on one or more interference signal(s) in which one or more reflected light(s), obtained from the measuring light reflected on the sample, and the reference light are interfering; a motion contrast calculator (S40, S70) that is designed to continuously calculate one or more first motion contrast(s) and one or more second motion contrast(s), among the irradiation points, one irradiation point disposed on the blood vessel being defined as a first irradiation point, and another irradiation point disposed on the blood vessel, that passes through the first irradiation point, and being different from the first irradiation point being defined as a second irradiation point, and the one or more first motion contrast(s) being one or more motion contrast(s) calculated based on the one or more interference signal(s) at the first irradiation point, and the one or more second motion contrast(s) being the one or more motion contrast(s) calculated based on the one or more interference signal(s) at the second irradiation point; a waveform creator that is designed to create, based on a calculation result obtained by the motion contrast calculator (S40, S70), a first motion contrast waveform, indicating chronological change in the one or more first motion contrast(s), and a second motion contrast waveform, indicating a chronological change in the one or more second motion contrast(s); a time lag calculator (S100, S110) that is designed to calculate time lag that is temporal lag between the first motion contrast waveform and the second motion contrast waveform created by the waveform creator; a distance calculator that is designed to calculate a blood vessel distance along the blood vessel from the first irradiation point to the second irradiation point; and a speed calculator that is designed to calculate, based on the time lag calculated by the time lag calculator (S100, S110) and the blood vessel distance calculated by the distance calculator, pulse wave velocity that is velocity of a pulse wave transmitted inside the blood vessel.