The objective of this study was the acoustic analysis of vocalizations of domestic dogs when they want to play with humans. Using a digital camcorder and microphone, we recorded and acoustically analyzed the vocalizations of six 7-month-old dogs (beagle) when they wanted to play with humans. The vocalizations were classified into five types, namely, barking (type Ⅰ, type Ⅱ), whining (type Ⅰ, type Ⅱ), and howling, based on the shapes of waveforms and spectrograms. There was a significant difference in the fundamental frequency (p<0.01), intensity (p<0.0001), 1st formant (p<0.001), 2nd formant (p<0.0001), 3rd formant (p<0.001), and 4th formant (p<0.05) among the vocalizations, whereas the duration was not different (p<0.05). Whining type I showed high values in the fundamental frequency and 3rd formant, while whining type II showed high values in the fundamental frequency and 1st, 2nd, and 4th formant. Further, bark types I and II showed high intensity values, with bark type II having a high value in the 1st formant. Finally, whining showed high values in the 4th formant only and significantly lower values in the 1st and 2nd formants than other vocalizations. Domestic dogs mainly exhibited barking and whining with differences in characteristics of fundamental frequency, intensity, and formant dispersion when they wanted to play with humans during the experiment. Accordingly, we suggest that vocalization could be a useful method for identifying dogs’ intentions or emotional state in a non-invasive manner.