To provide a sound insulating cover for an injector capable of effectively insulating sound in a manner that limitation of form of an engine is small.

The sound insulating cover for the injector includes a resin cover body arranged above a cylinder head and having an opening for avoiding interference with the injector on mounting and a rubber sound insulating cap detachably engaged and held with the opening of the cover body. The sound insulating cap is a mold member including a cap body part in a bottomed cylinder shape of which lower part is opened, an engaging part, arranged at an outer circumference of a lower part of the cap body part for engaging with the opening of the cover body, a window part arranged in a side wall of the cap body part and a tongue part extending from a lower end part of the window part to outside of the cap body part. A reinforcing rib for reinforcing the cap body part is arranged for an inner circumference of the cap body part. A slit for dividing the tongue part into two parts along the extending direction of the tongue part may be formed in the tongue part.