Provided are a mobile inspection device, a mobile inspection method, and a method for manufacturing a steel sheet with which it is possible to suitably inspect an inspection subject upon simplifying a device configuration and greatly reducing the size/weight of a device. A mobile inspection device (20) comprises a mobile inspection device body (30) that inspects defects in an inspection subject (S) while moving over a surface (Sa) of the inspection subject (S). The mobile inspection device body (30) is provided with a platform vehicle (31) that moves over the surface (Sa) by means of at least two vehicle wheels (32) that are capable of forward and reverse rotation, and at least one inspection sensor (44) positioned on the front-end side or on the rear-end side of the platform vehicle (31). An inspection area of the inspection subject (S) is divided into two division areas (A1), (A2) sandwiching a straight line, and the platform vehicle (31) moves, in each of the two division areas (A1), (A2) that are divided, in a state in which the inspection sensor (44) is tilted toward side edges (A1a), (A2a) of the division areas (A1), (A2), the side edges (A1a), (A2a) being on the opposite sides of the division areas (A1), (A2) from the aforementioned straight line.