A coating method of a plastic parts comprises coating a primer paint on a work made of a black color family plastic, coating a color base paint containing a color pigment on a primer coating film formed by coating the primer paint, coating a base paint containing a effect pigment on a color base coating film formed by coating the color base paint, and coating a clear paint on a base coating film formed by coating the base paint. In the coating method, the primer paint contains a color pigment having L* value of 80 or more in CIE colorimetric system L*a*b*.