Construction machinery comprising: a lower travelling body; an upper slewing body attached to the lower travelling body in a rotatable manner about a slewing axis; distance detection means (14A to 14D) attached to the upper slewing body, the distance detection means (14A to 14D) being configured to detect a distance to an object to be detected, the object being located in a circumference of the lower travelling body about the slewing axis; a slewing angle detector configured to detect a slewing angle of the upper slewing body with respect to the lower travelling body; notification means (17, 18) configured to notify an operator of predetermined information; and a controller, wherein the controller is configured to specify an entry prohibited area in which ingress of the lower travelling body is prohibited, based on the distance detected by the distance detection means (14A to 14D), to determine whether the entry prohibited area exists within at least one range of a front side detection range from a front portion of the lower travelling body to a position separated by a predetermined distance to a forward side in a travelling direction, and a rear side detection range from a rear portion of the lower travelling body to a position separated by a predetermined distance to a reverse side in the travelling direction, to generate, when it is determined that the entry prohibition area exists within the at least one range, information about safety with reference to the travelling direction of the lower travelling body based on the entry prohibited area and the slewing angle detected by the slewing angle detector (14A to 14D), and when it is determined that the entry prohibited area exists within the at least one range, to output, to the notification means (17, 18), a command for notifying the operator of the determination. a lower travelling body; an upper slewing body attached to the lower travelling body in a rotatable manner about a slewing axis; distance detection means (14A to 14D) attached to the upper slewing body, the distance detection means (14A to 14D) being configured to detect a distance to an object to be detected, the object being located in a circumference of the lower travelling body about the slewing axis; a slewing angle detector configured to detect a slewing angle of the upper slewing body with respect to the lower travelling body; notification means (17, 18) configured to notify an operator of predetermined information; and a controller, wherein the controller is configured to specify an entry prohibited area in which ingress of the lower travelling body is prohibited, based on the distance detected by the distance detection means (14A to 14D), to determine whether the entry prohibited area exists within at least one range of a front side detection range from a front portion of the lower travelling body to a position separated by a predetermined distance to a forward side in a travelling direction, and a rear side detection range from a rear portion of the lower travelling body to a position separated by a predetermined distance to a reverse side in the travelling direction, to generate, when it is determined that the entry prohibition area exists within the at least one range, information about safety with reference to the travelling direction of the lower travelling body based on the entry prohibited area and the slewing angle detected by the slewing angle detector (14A to 14D), and when it is determined that the entry prohibited area exists within the at least one range, to output, to the notification means (17, 18), a command for notifying the operator of the determination.