Through the stacking technique of 2D materials, the interfacial polarization can be switched by an interlayer sliding, known as sliding ferroelectricity, which is advantageous in ultra-thin thickness, high switching speed, and high fatigue resistance. However, uncovering the relationship between the sliding path and the polarization state in rhombohedral-stacked materials remains a challenge, which is the key to 2D sliding ferroelectricity. Here, layer-dependent multidirectional sliding ferroelectricity in rhombohedral-stacked InSe (γ-InSe) is reported via dual-frequency resonance tracking piezoresponse force microscopy and conductive atomic force microscopy. The graphene/γ-InSe/graphene tunneling device exhibits a tunable bulk photovoltaic effect with a photovoltaic current density of ≈15 mA cm