A mobile alarm apparatus includes a detection apparatus for detecting positional changes of the alarm apparatus; an output apparatus for the output of alarm signals; and a control apparatus for controlling the output apparatus in dependence on detected positional changes. The control apparatus is operable in a monitoring mode and in an alarm mode. In the monitoring mode, the control apparatus is configured to control the output apparatus to output a pre-alarm and to change into the alarm mode when a detected positional change is within a first range of significance. In the alarm mode, the control apparatus is configured to change into the monitoring mode when a predefined time period has elapsed since the last output of an alarm signal and otherwise, when a detected positional change is within a second range of significance, to control the output apparatus to output a main alarm different from the pre-alarm.