member 24 to be separated from engagement piece 21 b impelling means 26 is formed in ring shape in plan view and is formed and positioned so as to be mutually symmetrical with respect to the centerline along the longitudinal direction of engaging member 24 one end of impelling means 26 facing engaging part main body 25 comes into contact with receiving part 14 d which is formed in upper case main body 14 and has an l shaped cross section in this way impelling means 26 maintains the prescribed elastic force between engaging part main body 25 and receiving part 14 d when the operator removes his hand from pressing part 23 a or closes cover 13 engaging member 24 is automatically restored to its original position by impelling means 26 thus making it possible to automatically engage cover 13 by engaging member 24 engaging member 24 fits main body lower part 28 snugly into opening 14 c in a state in which the part that comes into contact with receiving part 14 d of impelling means 26 is bent and after it is fitted in upper case main body 14 can be attached by releasing the bend of impelling means 26 and engaging said impelling means 26 into receiving part 14 d the operation of opening and closing cover 13 of such an entertainment device 1 is as follows first when cover 13 is closed fig2 and 4 that is if the tip 27 a of main body upper part 27 is engaged in recess 21 c of engagement piece 21 b then when the operator presses member 23 contact part 23 b of pressing member 23 is inserted into through hole 29 of.