A wavelength converting material includes a luminous core and a first protective layer. The first protective layer covers the luminous core, in which the first protective layer includes silicon dioxide, and in silicon atoms of the silicon dioxide, the silicon atom of the zeroth configuration (Q0) does not connect with any siloxy group, and the silicon atom of the first configuration (Q1) connects with one siloxy group, and the silicon atom of the second configuration (Q2) connects with two siloxy groups, and the silicon atom of the third configuration (Q3) connects with three siloxy groups, and the silicon atom of the fourth configuration (Q4) connects with four siloxy groups, in which a total amount of the silicon atoms of the third configuration and the fourth configuration is greater than a total amount of the silicon atoms of the zeroth configuration, the first configuration and the second configuration.