Provided is a vehicular operation pedal device having a fail-safe function to prevent backward movement of a step portion of an operation pedal mechanism at the time of a vehicle collision. A brake pedal device (1) includes a protrusion (90) which performs rotation restriction for preventing a rotating member (50) from rotating about a rotating shaft portion (14), and on which a restricting load (F2) acts by the rotation restriction. During the rotation restriction by the protrusion (90), a second load acts as the restricting load (F2) when a step portion (24) of an operation pedal mechanism (20) is fully stepped forward of a vehicle, and when the restricting load (F2) is greater than the second load, the rotation restriction is released due to deformation of the protrusion (90) by shearing or bending.