An installation structure including an acoustic transducer configured to operate in accordance with an audio signal for thereby vibrating a vibrated body being a soundboard of a musical instrument in a first direction, so as to permit the vibrated body to generate sounds, comprising: a magnetic-path forming portion fixedly disposed relative to a fixedly supporting portion and forming a magnetic path; a movable unit having an electromagnetic coupling portion electromagnetically coupled to the magnetic-path forming portion, the movable unit being configured to vibrate in the first direction when the electromagnetic coupling portion is driven by the magnetic-path forming portion in response to a drive signal based on the audio signal; a connector fixed to the vibrated body, the connector connecting the movable unit to the vibrated body for transmitting vibration of the movable unit to the vibrated body; and at least two restricting mechanisms (130, 53) fixedly disposed relative to the fixedly supporting portion and configured to restrict a movement of the movable unit in a second direction that intersects the first direction, wherein each of the at least two restricting mechanisms (130, 53) engages the movable unit at a position in the first direction at which each of the at least two restricting mechanisms is closer to the magnetic-path forming portion than to the vibrated body, characterized in that the installation structure further comprises at least one permission mechanism (K, K1, K2, K3) provided on at least one of the movable unit and the connector, the at least one permission mechanism being disposed between the vibrated body and the closest engaging position that is the closest to the connector among engaging portions at which the at least two restricting mechanisms (130, 53) respectively engage the movable unit, wherein the at least one permission mechanism is configured to permit at least a portion of the movable unit located on one of opposite sides of the closest engaging portion nearer to the connector to incline with respect to the first direction when the connector is displaced relative to the fixedly supporting portion within a predetermined range. a magnetic-path forming portion fixedly disposed relative to a fixedly supporting portion and forming a magnetic path; a movable unit having an electromagnetic coupling portion electromagnetically coupled to the magnetic-path forming portion, the movable unit being configured to vibrate in the first direction when the electromagnetic coupling portion is driven by the magnetic-path forming portion in response to a drive signal based on the audio signal; a connector fixed to the vibrated body, the connector connecting the movable unit to the vibrated body for transmitting vibration of the movable unit to the vibrated body; and at least two restricting mechanisms (130, 53) fixedly disposed relative to the fixedly supporting portion and configured to restrict a movement of the movable unit in a second direction that intersects the first direction, wherein each of the at least two restricting mechanisms (130, 53) engages the movable unit at a position in the first direction at which each of the at least two restricting mechanisms is closer to the magnetic-path forming portion than to the vibrated body, characterized in that the installation structure further comprises at least one permission mechanism (K, K1, K2, K3) provided on at least one of the movable unit and the connector, the at least one permission mechanism being disposed between the vibrated body and the closest engaging position that is the closest to the connector among engaging portions at which the at least two restricting mechanisms (130, 53) respectively engage the movable unit, wherein the at least one permission mechanism is configured to permit at least a portion of the movable unit located on one of opposite sides of the closest engaging portion nearer to the connector to incline with respect to the first direction when the connector is displaced relative to the fixedly supporting portion within a predetermined range.