A needle cap that can be attached to a syringe (160) having a neck provided with a needle, said needle cap comprising: - a locking collar (110) that can be attached to the neck of the syringe (160), said said locking collar (110) provided with a distal inclined ramp (114), - a device protector (120) provided with two channels (121), each channel (121) comprising a lower surface (128), - a locking ring (150) mounted on the locking collar at its distal end, and - a flexible member (130) interconnecting the locking collar (110) and the device guard (120), in which, when the needle cap is coupled to the syringe, the device protector (120) can move relative to the locking collar (110) from a first configuration where the device protector (120) is free to retract proximally to expose the needle to a second configuration where the device protector (120) is fixed In a position that covers the needle, the device protector (120) is disengaged from the first configuration when the device protector (120) moves proximally allowing the device protector (120) to move distally under the push of the flexible member (130) to the second configuration, characterized in that: - the distal inclined ramp (114) of the locking collar (110) has a proximal flat surface (115), - the device protector (120) is provided with two arms of flexible locking (122), - the locking ring (150) contains two tabs (151) and two opposite projections (156), in which the two tabs (151) of the locking ring (150) are seated within the two channels (121) of the device protector (120), such that, when the device protector (120) moves proximally, the two tabs (151) of the locking ring (150) slide into the two channels ( 121) until contacting the bottom surface ( 128) of the channels (121), thereby transporting the locking ring (150) with the device guard (120) proximally to the distal inclined ramp (114) and to the proximal flat surface (115) of the locking collar (110) where a lower surface (154) of the locking rin
