In order to specify the uncertainty relation for a particle confined in a finite square well
potential we derived the standard deviation of momentum ##IMG##
[http://ej.iop.org/images/0143-0807/38/6/065402/ejpaa8417ieqn1.gif] {${\rm{\Delta }}p$} and that of
position ##IMG## [http://ej.iop.org/images/0143-0807/38/6/065402/ejpaa8417ieqn2.gif] {${\rm{\Delta
}}x.$} It is shown that ##IMG## [http://ej.iop.org/images/0143-0807/38/6/065402/ejpaa8417ieqn3.gif]
{${\rm{\Delta }}p$} has a peak as a function of the well width and both ##IMG##
[http://ej.iop.org/images/0143-0807/38/6/065402/ejpaa8417ieqn4.gif] {${\rm{\Delta }}x$} and ##IMG##
[http://ej.iop.org/images/0143-0807/38/6/065402/ejpaa8417ieqn5.gif] {${\rm{\Delta }}p\cdot
{\rm{\Delta }}x$} have a dip in contrast to the case of the particle confined in an infinite square
well potential. We clarified that ##IMG##