In this article, we propose a novel method for facilitating underwater electromyographic measurement, without using an adhesive waterproof film. This method employs a waterproofed insulated electrode and an amplifier with high-input impedance. The prototypes of the components were assembled and used for electromyographic measurement of the gastrocnemius, tibialis anterior, and long fibular muscles during plantar flexion both in and out of water. Eight subjects participated in the experiment. For each measurement site, the integrated underwater electromyography (EMG) was compared with that performed out of water, and the attenuation rate was then calculated. The results showed that( 1 )the mean attenuation rate of underwater EMG among the eight subjects was -1.58%, and( 2 )depending on the conditions, only two or three subjects showed significant attenuation at any of the three sites. In contrast, when non-waterproofed, disposable electrodes and a commercially available amplifier were used for electromyographic measurement, all eight subjects showed significant attenuation in underwater EMG at all three sites, with a mean attenuation rate of 80.5%. These results indicate that the proposed method is promising for underwater electromyographic measurement. In addition, it requires no waterproofing preparations, which might cause skin irritation and/or damage, thus allowing easier setup.