In this study, an SU(2) invariant multi-orbital Anderson impurity model is discussed to obtain the electronic properties of metalloproteins. Metalloproteins are organic molecules containing transition metal atoms. They have important roles in the chemical reactions taking place in organisms. The electronic properties of metalloproteins can be modeled by an effective Anderson impurity model. The effective Anderson impurity model can be studied with the quantum Monte Carlo algorithm developed by Hirsch and Fye (1986). In the quantum Monte Carlo simulations of the Anderson impurity model so far, only the longitudinal component of the Hund’s coupling term which arises from the Coulomb interactions between the 3d orbitals is taken into account. Spin-flip and pairhopping terms (the transverse terms of the Hund’s coupling) are not considered. They are required to make the Hamiltonian SU(2) invariant, which is related to the spin rotations, so that the Hamiltonian is more realistic. The treatment of the transverse Hund’s coupling with the Hirsch-Fye algorithm has been difficult because of the problems encountered in the Trotter decomposition. Instead, a series expansion method was developed by Sakai et al. (2006). Here, we combine the Hirsch-Fye quantum Monte Carlo algorithm with the series expansion method to study the SU(2) invariant multi-orbital Anderson impurity model. Therefore, we present results from quantum Monte Carlo simulations with the new algorithm.