An apparatus for detecting the opening and closing of a slide-type mobile communication terminal having a main body and a sub-body mounted on the main body. The apparatus includes a signal generating element of bar-type provided in the sub-body for generating a predetermined signal; a first and a second signal sensor provided at two positions separated by a predetermined interval in the main body so as to face the signal generating element respectively when the sub-body is slid up and down relative to the main body, the first and second signal sensors detecting the predetermined signal; and a control unit for performing corresponding functions according to the opening and closing operations of the mobile communication terminal represented by different signals generated by the first and second signal sensors.