Provided is a cylindrical vibrator for sex toy. The vibrator has two halves coupled together by snapping. The vibrator comprises a top cavity for receiving a sliding switch, a plurality of compartments wherein any two adjacent compartments are communicated through an groove, an conductive, flexible interconnection fastened on an inner wall and comprising an upper recess having its mouth urged against an inclined portion on a bottom of the switch in a non-operating position, one or more cells coupled in series, and a motor electrically coupled to both the interconnection and the cell. Sliding the switch from the non-operating position to an operating position will press the recess to contact a negative terminal of the below cell for forming a circuit to energize the motor.