The invention relates to the field of microbiological inspection instruments and apparatus, particularly to an automatic bacteria inoculator comprising an inoculator body, a test tube storage device, a culture dish transferring device, an inoculation device, sterilization devices, a clamping device and a cover fetching device, wherein the test tube storage device is arranged at the rear part of the inoculator body; the culture dish transferring device is mounted in front of the test tube storage device; the inoculation device is distributed on the right side of the test tube storage device; the sterilization devices are arranged on left and right sides of the scribing position of the inoculation device; the cover fetching device is mounted on the inoculator body; and the clamping device is mounted on the inoculator body. The automatic bacteria inoculator adopts instrument operation instead of manual operation, and can automatically sterilize the inoculation environment and a bacteria inoculation ring, shorten the whole inoculation time, improve the working efficiency of bacteria inoculation and scribing, and reach high precision and idealized inoculation effects during bacteria inoculation and scribing.