To improve readability of an indicator by providing a retainer capable of adjusting the height of the indicator at the rear range of an automobile and making the retainer movable between at least two end positions, when necessary.

A movable overturn protection device having an indicator 3 is constructed as a movable roll bar 1. An initial position and a service position are shown by reference numerals I and II. The indicator 3 includes a housing 3.1 and a plurality of indicating elements 3.2, and the indicating elements 3.2 are controlled by an electronic evaluation of a distance between a vehicle and a barrier and/or by a control circuit. An electric connection lead between the electronic evaluation and/or the control circuit and the indicating element 3.2 is provided inside the roll bar 1. The indicator 3 is provided at a center of the swingable roll bar 1. The overturn prevention device can be moved steplessly between the initial position I and the service position II by operation of a switch by a driver. Accordingly, the overturn device can be moved to a position that ensures reading of the indicator 3 causing no problem.