to access extreme confinement of photons into micro-or nanoscale region [3,10,11] above the light line within the radiation continuum. In general, EM wave is usually interpreted in terms of frequency spectrum, and it propagates as a spectral continuum above the light line in different media. Different orders of resonances may be found in the propagating continuum at specific frequencies described by i n n n 0 ω ω γ = + , where the real part indicates resonance frequencies and the imaginary part indicates the leakage rates of the n-order mode. [12] For a strongly confined mode, the leakage rate is significantly reduced, and goes to zero if photons are perfectly trapped in a so-called bound state in an ideal scenario. [13] However, such a bound state in the continuum (BIC) is not observable from the spectrum due to the nonradiative feature with vanishing spectral linewidth. As an embedded eigenvalue of the photonic system, [14] it becomes visible in the spectrum with a finite leakage rate as a quasi-BIC by introducing external perturbations. Such a BIC-inspired mechanism for light confinement allows a general strategy to access extremely high quality factor (Q, Q = ω 0 /2γ) resonance in optical cavities.Dielectric photonic crystals (PhCs) are an excellent platform to explore the BICs which largely avoid the intrinsic Ohmic loss for extremely high Q generation by exciting displacement current. [15,16] Nevertheless, the geometric size of unit cells in PhCs is usually at the scale of resonance wavelength, and resonant energy is thus loosely confined in the resonator cavity with a relatively large mode volume (V). In this condition, Purcell factor proportional to Q/V is largely reduced in the traditional PhCs despite a large Q, which hinders the efficient spontaneous emission rates in the context of cavity quantum electrodynamics. [17] An efficient approach to densely confine photons is by using metamaterials whose building blocks are in the subwavelength scale, and the resonant mode volume could be further reduced to a deep subwavelength scale by carefully designing the resonator geometry and mode properties. Here, we demonstrate dual symmetry-protected BICs in a subwavelength metamaterial that are independently induced by orthogonal polarizations of incident light. The features of the subwavelength BICs are experimentally observed in the terahertz spectrum by slightly breaking the C 2 symmetry with large Q factors. We also show the inverse square dependence of Q factor on the structural asymmetry parameter which describes a Bound state in the continuum (BIC) is a mathematical concept with an infinite radiative quality factor (Q) that exists only in an ideal infinite array of resonators. In photonics, it is essential to achieve high Q resonances for enhanced light-mater interactions that could enable low-threshold lasers, ultrasensitive sensors, and optical tweezers. Hence, it is important to explore BICs in different photonic systems including subwavelength metamaterials where symmetry-protected dual BICs exist. Th...