A signal output unit outputs an acquired signal. A signal attribute value display unit displays a value of an attribute related to an element constituting a target represented by the acquired signal or a signal generation source in a state in which a change instruction of the value of the attribute is able to be received. A changed attribute value acquisition unit acquires a changed value of the attribute when the change instruction of the value of the attribute is received. A change unit changes the value of the attribute for which the change instruction has been received on the basis of the changed value of the attribute acquired by the changed attribute value acquisition unit. A changed signal output unit outputs a changed signal in which the value of the attribute has been changed.