A keyboard device applicable to various kinds of applications with high responsivity is provided. The keyboard device includes keys to which key addresses are assigned and a memory in which data for determining whether a key has been depressed is writable and readable at an memory address corresponding to each of the key addresses. The device also includes a key capacitance detecting unit to detect a capacitance of the key corresponding to a selected key address, a capacitance-voltage converting unit to convert the capacitance of the key detected by the key capacitance detecting unit into a voltage, a data converting unit that reads threshold data in the memory address in the memory corresponding to the key address that is selected to convert the threshold data into analog data, and a depression determining unit that compares the analog data with the voltage to determine whether the key has been depressed.