A cordless telephone apparatus includes: a battery which is rechargeable with a direct current based on an electric energy supplied from an outside of the cordless telephone apparatus; a constant current circuit which limits the direct current charged into the battery to a constant current; a voltage-dividing resistor which divides a direct voltage inputted into the constant current circuit; an A/D converter which converts a value of the direct voltage divided by the voltage-dividing resistor into digital data; a charging-state acquiring portion which acquires a charging state of the battery based on the digital data from the A/D converter; and a charging-state informing portion which informs the charging state of the battery acquired by the charging-state acquiring portion.