[Object] Provided are a swallowing estimation device that can maintain high swallowing estimation accuracy even when information for swallowing estimation is collected in a living environment, and an information terminal device and a program that are to be used therefor. [Solution] A swallowing estimation device includes: a sound detection part configured to detect sound of a larynx portion; a respiration detection part configured to detect respiration; and a swallowing estimation part configured to estimate swallowing based on sound information outputted from the sound detection part and based on respiration information outputted from the respiration detection part. The swallowing estimation part obtains a value of a parameter for swallowing estimation with respect to a biological sound generation interval that corresponds to an apneic interval longer than or equal to 400 msec, and estimates whether swallowing has occurred in the biological sound generation interval based on whether the obtained value of the parameter satisfies a swallowing determination condition.