A method for manufacturing a wavelength converting member comprising a polycrystalline sintered ceramic comprising a garnet phase having the compositional formula: (A 1-x B x) 3 C 5 O 12 wherein A is at least one rare earth element selected from the group consisting of Y, Gd, and Lu, B is at least one rare earth element selected from the group consisting of Ce, Nd, and Tb, C is at least one element selected from the group consisting of Al and Ga, and x is a number from 0.002 to 0.2, and at least one phase selected from the group consisting of perovskite, monoclinic and silicate phases, fine grains of phase being included in a matrix of crystal of phase and dispersed in a matrix of crystal of phase, wherein method comprises the steps of i) mixing powders of the elements contained in the garnet phase so as to give a desired content ratio and firing the mixture in ambient atmosphere or vacuum at a temperature of 900 to 1,500°C for 10 minutes to 8 hours to obtain a first source powder of the garnet phase-forming mono-phase composition, ii) where the phase is a perovskite or monoclinic phase, mixing powders of the elements contained in the perovskite or monoclinic phase so as to give a desired content ratio and firing the mixture in ambient atmosphere or vacuum at a temperature of 900 to 1,500°C for 10 minutes to 8 hours to obtain a second source powder of the perovskite or monoclinic phase-forming mono-phase composition, or where the phase is a silicate phase, preparing a powder of a silicon-containing compound as a second source powder, iii) mixing the first source powder with the second source powder, iv) shaping the powder mixture into a formed body, and v) heating the body for sintering. a garnet phase having the compositional formula: (A 1-x B x) 3 C 5 O 12 wherein A is at least one rare earth element selected from the group consisting of Y, Gd, and Lu, B is at least one rare earth element selected from the group consisting of Ce, Nd, and Tb, C is at least one element selected from the group consisting of Al and Ga, and x is a number from 0.002 to 0.2, and at least one phase selected from the group consisting of perovskite, monoclinic and silicate phases, fine grains of phase being included in a matrix of crystal of phase and dispersed in a matrix of crystal of phase, wherein method comprises the steps of i) mixing powders of the elements contained in the garnet phase so as to give a desired content ratio and firing the mixture in ambient atmosphere or vacuum at a temperature of 900 to 1,500°C for 10 minutes to 8 hours to obtain a first source powder of the garnet phase-forming mono-phase composition, ii) where the phase is a perovskite or monoclinic phase, mixing powders of the elements contained in the perovskite or monoclinic phase so as to give a desired content ratio and firing the mixture in ambient atmosphere or vacuum at a temperature of 900 to 1,500°C for 10 minutes to 8 hours to obtain a second source powder of the perovskite or monoclinic phase-forming mono-phase composition, or where the phase is a silicate phase, preparing a powder of a silicon-containing compound as a second source powder, iii) mixing the first source powder with the second source powder, iv) shaping the powder mixture into a formed body, and v) heating the body for sintering. i) mixing powders of the elements contained in the garnet phase so as to give a desired content ratio and firing the mixture in ambient atmosphere or vacuum at a temperature of 900 to 1,500°C for 10 minutes to 8 hours to obtain a first source powder of the garnet phase-forming mono-phase composition, ii) where the phase is a perovskite or monoclinic phase, mixing powders of the elements contained in the perovskite or monoclinic phase so as to give a desired content ratio and firing the mixture in ambient atmosphere or vacuum at a temperature of 900 to 1,500°C for 10 minutes to 8 hours to obtain a second source powder of the perovskite or monoclinic phase-forming mono-phase composition, or where the phase is a silicate phase, preparing a powder of a silicon-containing compound as a second source powder, iii) mixing the first source powder with the second source powder, iv) shaping the powder mixture into a formed body, and v) heating the body for sintering.