key 300 is released therefore the mechanical key 300 is able to be pulled out from the upper case 400 see an arrow 714 the mechanical key 300 pulled out from the upper case 400 in this manner is able to be used independently as a matter of course and may also be used by setting the head portion 301 of the mechanical key 300 to the attachment and detachment port 405 of the upper case 400 as in the second related art described at the beginning fig1 is a drawing illustrating a procedure of setting the head portion 301 of the pulled out mechanical key 300 into the attachment and detachment port 405 of the upper case 400 for use a cross sectional view which is similar to fig3 as shown in this drawing it is also possible to invert the mechanical key 300 pulled out from the upper case 400 set the head portion 301 to the attachment and detachment port 405 of the upper case 400 and hold the upper case 400 to operate the mechanical key 300 if necessary in this configuration the portable device 100 of this embodiment achieves the following advantages a when the mechanical key 300 is stored in the main body 200 the mechanical key 300 is locked by the key lock mechanism 600 therefore the mechanical key 300 is prevented from coming apart unintentionally b by sliding the operating unit 629 of the knob 601 with a fingertip or the like the mechanical key 300 is able to be pulled out from the main body 200 by one touch operation c the mechanical key 300 may be used in a state in which the.