A method for detecting an object and a touchable device are presented, which is capable of detecting an object having a fingerprint feature on an operation interface of the touchable device. An image sensor is used for acquiring acquiring an image on the operation interface, and the acquired image is converted into a signal denoted in a frequency domain by using a frequency conversion function. Signals at a medium-high frequency (MHF) signal region among the signals of the frequency domain are analyzed, so as to generate a first signal and a second signal according to a distribution of the signals of the frequency domain. The first signal indicates existence of the object on the operation interface, and the second signal indicates inexistence of the object on the operation interface.