Disclosed is a process for producing propylene by contacting at least one starting material selected from ethylene and ethanol with a catalyst containing a medium pore size zeolite in a fluidized bed reactor, wherein the catalyst fulfills the following requirements (a) to (e): (a) 90 mass% or more of particles of the catalyst have particle sizes ranging from 10 to 197 µm; (b) particles of the catalyst have a bulk density ranging from 0.7 to 1.1 g/cm3; (c) particles of the catalyst having particle sizes of 30 to 70 µm have an average compressive ultimate strength of 15 MPa or more, and 90 mass% or more of particles of the catalyst have a compressive ultimate strength of 10 MPa or more; (d) the catalyst has an angle of repose of 20 to 30°; and (e) each of pores having pore radii ranging from 2000 to 20000 nm has a pore volume of 0.050 c/g or less.
