To provide a simple partition panel structure, in which a decorated panel can be easily mounted on a frame and does not come off easily after once it was mounted.

A plurality of stepped pins 9 having a head with a large diameter are arranged in a projected manner either on at least one side of the frame 2, or on one side of a decorated panel 3 opposed to the above side of the frame, the decorated panel mounted on the one side of the frame 2. On the side other than the pin-arranged-side, engaging holes 14, 15 with long holes 14a, 15a are drilled to be able to engage with the stepped parts of the stepped pins 9. Each stepped pin 9 is engaged with the far end of the long hole of respective engaging holes corresponding to each stepped pin 9 to mount the decorated panel 3 on the frame 2. An end cover 4 is fitted on the end face formed on the direction in which the decorated panel 3 is removed from the frame 2, the end cover 4 projected outward from one side of the frame 2 and preventing the decorated panel 3 from coming off the frame 2.