A developer spreading device comprising: a film pack room into which an instant film pack is loaded, the instant film pack including a plurality of film units each having a developer pod containing a developer, a case which includes an exposure opening and a slit-shaped discharge port and accommodates the plurality of film units laminated on top of each other, and a film cover which lighttightly blocks the exposure opening by covering an exposure surface of the film unit and is ejected through the discharge port; characterised in that the developer spreading device further comprises: a transport roller pair that transports the film unit or the film cover discharged through the discharge port while pinching both side edge portions of the film unit or the film cover; and a spreading roller pair that is disposed on a downstream side of the transport roller pair in a transport direction perpendicular to a width direction of the exposure surface, and spreads the developer into the film unit by crushing the developer pod, wherein the case includes a pair of light shielding grooves formed in both sides of the exposure opening and an inner wall surface facing the film cover, the film cover includes a pair of light shielding ribs which is inserted into the pair of light shielding grooves and extends in a discharge direction in a case where the film cover is discharged through the discharge port, and the transport roller pair includes a capstan roller that includes a pair of roller members and a rotational shaft which holds the roller members, and a first distance which is a space between inner edges of the pair of roller members is greater than a second distance which is a space between outer edges of the pair of light shielding ribs. a film pack room into which an instant film pack is loaded, the instant film pack including a plurality of film units each having a developer pod containing a developer, a case which includes an exposure opening and a slit-shaped discharge port and accommodates the plurality of film units laminated on top of each other, and a film cover which lighttightly blocks the exposure opening by covering an exposure surface of the film unit and is ejected through the discharge port; characterised in that the developer spreading device further comprises: a transport roller pair that transports the film unit or the film cover discharged through the discharge port while pinching both side edge portions of the film unit or the film cover; and a spreading roller pair that is disposed on a downstream side of the transport roller pair in a transport direction perpendicular to a width direction of the exposure surface, and spreads the developer into the film unit by crushing the developer pod, wherein the case includes a pair of light shielding grooves formed in both sides of the exposure opening and an inner wall surface facing the film cover, the film cover includes a pair of light shielding ribs which is inserted into the pair of light shielding grooves and extends in a discharge direction in a case where the film cover is discharged through the discharge port, and the transport roller pair includes a capstan roller that includes a pair of roller members and a rotational shaft which holds the roller members, and a first distance which is a space between inner edges of the pair of roller members is greater than a second distance which is a space between outer edges of the pair of light shielding ribs. a transport roller pair that transports the film unit or the film cover discharged through the discharge port while pinching both side edge portions of the film unit or the film cover; and a spreading roller pair that is disposed on a downstream side of the transport roller pair in a transport direction perpendicular to a width direction of the exposure surface, and spreads the developer into the film unit by crushing the developer pod, wherein the case includes a pair of light shielding grooves formed in both sides of the exposure opening and an inner wall surface facing the film cover, the film cover includes a pair of light shielding ribs which is inserted into the pair of light shielding grooves and extends in a discharge direction in a case where the film cover is discharged through the discharge port, and the transport roller pair includes a capstan roller that includes a pair of roller members and a rotational shaft which holds the roller members, and a first distance which is a space between inner edges of the pair of roller members is greater than a second distance which is a space between outer edges of the pair of light shielding ribs.