A tape cassette comprises a supply and a take-up reel on which tape is wound, a cassette casing for rotatably enclosing the reels therein, a plurality of tape guide pins, each being press-fitted through the inner wall of the casing, for defining a tape path for the tape travelling between the pair of reels. The press-fit section of each guide pin is formed in a predetermined taper in such a manner as to gradually decrease its outer diameter towards its end. The straight press-fit section of the guide pin is formed in such a manner as to include a predetermined geometry of chamfered circumference at its end. In a tape guide pin used in conjunction with a tape guide roller, grease having a predetermined viscosity coefficient is disposed between the associated pin and roller. An electrical insulating cover is provided for surrounding the exposed underside of the electrically conductive lower half of the casing.