Purpose: Measurement of swallowing muscle mass is important in determining sarcopenic dysphagia. Ultrasound equipment can measure the cross-sectional area of the swallowing muscles, but the inter-instrument reliability is unknown. In this study, the inter-instrument reliability was investigated. Methods: Three ultrasound devices were used to measure the geniohyoid muscle in 16 healthy participants, and their reliability was evaluated. The LogiQeV2, which has already been used to calculate cut-off values for the muscle mass of the geniohyoid muscle, was used as the key device. The reliability of the Sonosite iViz and the TUP-C035J for LogiQeV2 was analysed, respectively. Intra-class correlation coefficients (ICC) and Bland-Altman plots were used for the analysis. Results: The ICC between LogiQeV2 and Sonosite iViz was 0.976. One data point deviated from the Limit of agreement. The ICC between LogiQeV2 and TUP-C035J was 0.979. Ninety-four per cent of the data fell within the limit of agreement. From the result of the ICC and Bland-Altman plot, errors were judged to be within the acceptable range for practical purposes. Conclusion: The inter-instrument reliability of three ultrasound systems for cross-sectional area of geniohyoid muscle was confirmed. In the clinical setting, ultrasound systems can be widely used to measure the swallowing muscle mass.