Technologies are generally described for measuring hair moisture using a hair moisture measuring device including a vibrator, a sound wave detector, a heater, and/or a processor. The vibrator may generate and propagate first sound waves through a strand of hair, which may be detected by the sound wave detector. The processor may then measure a first time-delay between the first sound waves and the first driving signals. After heating the hair by the heater, the vibrator may generate and propagate second sound waves through the strand of hair, which may be detected by the sound wave detector. The processor may measure a second time-delay between the second sound waves and the second driving signals, and also measure an amount of the moisture by calculating a time-delay difference between the first time-delay and the second time-delay.