A holder mechanism for holding a handheld device is provided which includes a holder base and a gripping assembly. The gripping assembly is movably mounted on the holder base. The gripping assembly includes an elastic element, a first gripping module, and a second gripping module. The elastic element has a first end fixed to the first gripping module and a second end fixed to the second gripping module. Whereby, the second gripping module can move relative to the first gripping module to grip the handheld device when the elastic element is elastically deformed to apply a resilient force to the second gripping module.