We demonstrate the simultaneous magneto-optical trapping (MOT) of Rb and Sr and examine the characteristic loss of Rb in the MOT due to photoionization by the cooling laser for Sr. The photoionization cross section of Rb in the 5P 3/2 state at 461 nm is determined to be 1.4(1)×10-17 cm2. It is important to consider this loss rate to realize a sufficiently large number of trapped Rb atoms to achieve a quantum degenerate mixture of Rb and Sr. © 2013 American Physical Society.