An electronic measurement device comprising: a display unit; an operation unit comprising a plurality of software keys for performing operation functions for operating the electronic measurement device; and a central processing unit configured to control the display unit to display measurement data on the display unit, wherein: the electronic measurement device has a lock function of locking operation functions on the operation unit such that the operation functions, except for an unlocking function, are temporarily inoperable, the electronic measurement device is further configured to perform a process of registering software keys which are operable even in a lock state so that at least one of the operation functions associated with the registered software key, is set to be selectively operable even in the lock state, in addition to the unlocking function; the central processing unit is configured so that the at least one of the plurality of software keys associated with the operation function, that is set to be selectively operable, is displayed in a manner that is distinguishable from software keys associated with operation function that is temporarily inoperable; the electronic measurement device further comprising storage unit configured to store information on whether each key is operable in the lock state and for retaining this information even after power is cut off; and after the power is cut off in the lock state, the electronic measurement device is configured to be booted during a next power-on while keeping the lock state during power-off so that the lock state is not released. a display unit; an operation unit comprising a plurality of software keys for performing operation functions for operating the electronic measurement device; and a central processing unit configured to control the display unit to display measurement data on the display unit, wherein: the electronic measurement device has a lock function of locking operation functions on the operation unit such that the operation functions, except for an unlocking function, are temporarily inoperable, the electronic measurement device is further configured to perform a process of registering software keys which are operable even in a lock state so that at least one of the operation functions associated with the registered software key, is set to be selectively operable even in the lock state, in addition to the unlocking function; the central processing unit is configured so that the at least one of the plurality of software keys associated with the operation function, that is set to be selectively operable, is displayed in a manner that is distinguishable from software keys associated with operation function that is temporarily inoperable; the electronic measurement device further comprising storage unit configured to store information on whether each key is operable in the lock state and for retaining this information even after power is cut off; and after the power is cut off in the lock state, the electronic measurement device is configured to be booted during a next power-on while keeping the lock state during power-off so that the lock state is not released. the electronic measurement device has a lock function of locking operation functions on the operation unit such that the operation functions, except for an unlocking function, are temporarily inoperable, the electronic measurement device is further configured to perform a process of registering software keys which are operable even in a lock state so that at least one of the operation functions associated with the registered software key, is set to be selectively operable even in the lock state, in addition to the unlocking function; the central processing unit is configured so that the at least one of the plurality of software keys associated with the operation function, that is set to be selectively operable, is displayed in a manner that is distinguishable from software keys associated with operation function that is temporarily inoperable; the electronic measurement device further comprising storage unit configured to store information on whether each key is operable in the lock state and for retaining this information even after power is cut off; and after the power is cut off in the lock state, the electronic measurement device is configured to be booted during a next power-on while keeping the lock state during power-off so that the lock state is not released.